When Science meet Magic
by Erzats
Summary: When Shocker send themselves to another world, the Riders choose to send Sento Kiryu, aka Kamen Rider Build, to find them. But how can a narcissistic physician survive in a world of magic ? Sento-centric, Nalu. First story, so advices are welcome. (Now adopted by itoonia, i'm also starting to work on a new version of this fic)
1. Chapter 1 : Let's go to another world !

**I don't own Fairy Tail or Kamen rider Build.**

 **Chapter 1 : Lets go to another world**

/-Somewhere in Japan -/

Sun was just rising, and yet someone was coming, driving a quite strange red bike. In fact, it had a big toothed wheel on the front and what seems to be a kind of big yellow bottle coming out of the end. The driver was approching what looked like an old factory. He stopped just outside, pulled off his helmet and enter the building. After going down stairs for several minutes, he opened a door and was faced with a big, swirling blue wormhole, or at least it looked like one.

\- "Ah, you are finally here, Sento Kiryu." said a voice

Turning to his right, Sento was now in front of the two men who called him here. The first one, the one who talked, was fully dressed in leather and quite old but you could see in his eyes that even if he was old, he could easily fight in more than one ways, and for good reason. His name was Takeshi Hongo, aka Kamen Rider Ichigo, the oldest of those warrior, and probably one of the most powerful. By his side was a young man dressed with a dark grey blazer, matching pants and shoes and a pink shirt. He also had an old red camera hanging around his neck. He was Tsukasa Kadoya, aka Kamen Rider Decade.

The young man, called Sento Kiryu, approached the two man, but without taking his eyes of the wormhole.

\- "I tried to come as fast as possible, Takeshi, but now I know why" said Sento. "I'm sure its for this thing, isn't it ?"

\- "To the point, as I see" noticed Tsukasa. "Well, you are right, that's the reason but it's just a …"

\- "He isn't listening, Tsukasa" indicated Takeshi.

Tsukasa indeed noticed that Sento was litteraly all over the hole, a tuft of his hair high in the air from the excitation as he began to elaborate theories after theories. Takeshi didn't know what amused him the most : Sento's behavior or Tsukasa's facial expression.

\- "KIRYU SENTO, ARE YOU LISTENING OR NOT ?! " shouted Tsukasa.

\- "Eh ?", answered the physicist while turning back, remembering that he wasn't alone. "Oh, no need to explain anything to me. If you called me, it's necessarily for my genius. I am the only one who can truly understand what that thing is, isn't it ?"

\- "We didn't call you here for your brain, Sento", answered Takeshi.

At that, Sento instantly calmed down, turning back again to the Riders, his tuft of hair falling back, as if it was deflated.

\- "What ? But I'm here then ? ", asked the physicist.

\- "If we say that this thing was created by Shocker, you will listening calmly ?", asked Tsukasa.

Sento lift his head up, then looked at the Riders straight into their eyes.

-"Tell me everything", asked Sento.

Takeshi then began to explain what was the situation.

\- "A few weeks ago, we noticed that Shocker, even if they stayed in the shadow after their last defeat, were moving a lot more than before. I then asked many Riders, including Tsukasa, to discover where they were and when we found them, we were ready to surprised them. But as soon as we arrived, all of their troops, or at least a big part of it, jumped through this portal. We looked around for information and we found out that this thing is a portal to another world."

Sento's eyes widened at this revelation.

\- « Another world ? What do you mean ? » asked the physicist.

\- "We do not know much more unfortunately." Answered the photograph. "We know nothing about this world."

\- "Well, we good let them there. I mean, we got rid of them, no ?"

\- "If that was the case, we would have leaved this place already." Said Takeshi. "But Shocker didn't crossed this gate because we had them cornered : they were going to do it anyway. Which make me think that even if they don't know about this world, they wanted to go there and they probably have a way to come back."

\- "And seeing you have one hell of a brain," continued Tsukasa "you can probably imagine what will happen if they come back here with a power from another world."

Indeed, Sento could perfectly see in his mind what kind of thing could happen with this scenario, and knowing Sento and his over-working brain, he probably was thinking about it A LOT.

\- "Ok then, we can let them do what they want, but what can we do", he asked.

\- "Simple : we send you there", answered Tsukasa

\- "… Me ? In an unknow world ?", asked Sento, something strange starting to shine in his eyes.

\- "Indeed, that's the best choice" nodded Takeshi. "We don't have what we need to build something that will help you to come back from there, but as a physicist, you, out of all the other Rider, have the best chance in finding a way home. It will be even easier since Shocker probably have a way to come back so if you can get the data from them, you'll be able to make your own way back. But it will be a dangerous journey. After all, we know nothing of the place you will be in and …".

\- "He's not listening to you anymore, Takeshi", pointed out Tsukasa

Indeed, Sento had turned et was talking to himself, asking himself all the question he could think of about that world. You could hear "Is it a futuristic universe ? If that's the case, how advanced are they ? Are they more about mechanic ? or Chemistry ? Aaaah~, so many possibilities !" coming out of his mouth so fast you could barely understand what he was saying.

\- "… Sento ?" asked Takeshi.

\- "I'LL DO IT !", shouted Sento with enthusiasm.

\- "OoooK, then I guess you can go prepare yourselves and come back tomorrow.", continued Tsukasa, still shocked by Sento's behavior.

\- "OK" was the young man answer as he was speeding away.

The two Riders watched him leave, still surprised by the enthusiasm.

\- "You…think he'll be fine ?", asked Decade to Ichigo

\- "… Yes. I'm … sure we can trust him", answered Takeshi

Tsukasa, having noticed the hesitation in his comrade voice, looked to the portal, hoping everything will be fine.

/-Next morning-/

Sento came back to the warehouse the next day, but he wasn't alone this time. He was followed by Ryuga Banjou, aka Kamen Rider Cross-Z, Misora Isurugi and Sawa Takigawa, the three of them having insisted on accompanying him.

\- "Why did you come again ?", asked Sento, clearly annoyed that they had convinced him to let them come.

\- "To know exactly what you are getting yourself into, Baka", answered Misora

\- "She's right. You really think we are gonna let you go who know where with ALL the Fullbottles, your Driver and even the Sparkling Bottle and the Hazard Trigger without any further explication ?", completed Ryuga. "And since you've been called by Ichigo and Decade, it must be something big."

\- "I already told you what I'm gonna do.", countered Sento. "I'm going somewhere to fight bad guys".

\- "THAT'S NOT AN EXPLANATION ! », shouted Ryuga

\- "That's enough for someone with a brain like yours.", retorted Sento

\- "I'M GONNA KILL YOU ? YOU LITTLE …"

\- "Stop that now, it's neither the moment nor the place.", said Sawa trying to stop the boys.

\- "Anyway, what's YOUR reason to come with us, Sawa ?", asked Misora to change the subject.

\- "I'm gonna have an interview with those two Riders", she answered with confidence

Not expecting a reason so stupid and serious at the same time, the three other fell to the ground.

\- "What ? Meeting two legendary Riders, it's gonna be the interview of my life !", telled Sawa with stars in her eyes.

\- "Calm down now, we are here.", noticed the dragon Rider.

Indeed, they were at the door. Sawa straightened her clothes, check herself in her pocket mirror one last time before opening the door. What she saw behind it made her heartbeat skyrocket, but what she felt in the air made her feel uneasy.

The raise of her heartbeat because Decade and Ichigo weren't the only Riders here. All the Rider from the Neo-Heisei were here : Shotaro Hidari and Philip, Eiji Hino, Gentaro Kisaragi, Haruto Soma, Kouta Kazuraba, Shinnosuke Tomari, Takeru Tenkuji and Emu Hojo. It could be the interview of a lifetime for Sawa. But the air was heavy. They all had a frown on their faces, a sign that they were just denied something. When Ryuga saw the vortex, he asked :

\- "What is that ? "

\- " It's a portal to an unknow world.", answered Shotaro

\- "What ? Really ?", asked Misora

\- "Yeah, and Sento was chosen among all of us to go to this world, find Shocker and bring them back", completed Philip.

\- "What ? And he is going alone ? Are you out of your mind ?", Asked Sawa with surprised and anger in her voice

\- "Yeah, at least let me go with him.", demanded Ryuga.

\- "We can't. None of us can.", answered Eiji

\- "But why ?"

\- "I'll never leave a buddy whose in a pinch." Affirmed Gentaro. "But the portal isn't strong enough."

\- "It seems to have the energy to take just one person.", said Haruto "But we still have hopes that he will came back"

\- "Sento is the most intelligent of all the Riders, if there is someone who can find a way to come back, even in a world he doesn't know, it's him." Said Kouta with conviction.

\- "He might even be able to contact us with his Build Phone, so we could always help him if he need informations. We'll never be far away. " continued Shinnosuke.

\- "Moreover, there is a great chance that this world might be inhabited and as a Kamen Rider, it will be his job to protect them from Shocker." Said Takeru.

\- "To have fought by his side, I know that he'll succeed in all of his missions : finding Shocker and bringing them back", said Emu with high confidence.

After hearing the opinions of the other Riders, Sento's friends calmed down.

\- "You better come back, you hear me ?" asked Ryuga

\- "Loud and clear." Answered Sento. He then turned to Sawa and Misora, who hasn't said anything.

\- "Don't worry, I'll came back in no time. After all, I'm the greatest genius ever, right ?", asked Sento.

The girls smiled a little, hearing Sento's typical narcism, and lift their head.

\- "Yeah. ", they nodded at the same time.

\- "Sento, it's time.", said Takeshi

At that, Sento put his bag full of his devices on his back, walked to the portal, then turned one last time, facing his friends and the Riders.

\- "Be strong, and make the values of Kamen Riders shine strong, Sento Kiryu." Asked Ichigo. "Go and come back with victory, KAMEN RIDER BUILD ! »

Everyone then echoed that shout, with cheering of their own :

\- "Make them count up their sins !", said Shotaro and Philip

\- "May their greed be their fall !", said Eiji

\- "Let our friendship follow us to the end of the universe !", said Gentaro

\- "It's showtime and you're the star !", said Haruto

\- "Let that be your stage, now !", said Kouta

\- "Go on, at top gear !", said Shinnosuke

\- "Your life is gonna burn bright !", said Takeru

\- "You'll clear this with no continue !", said Emu

\- "Come back quickly, Sento ! », said Ryuga, Misora and Sawa in one voice

Sento smiled at everyone then turned to the portal.

"Now, shall we begin the experiment ?", said Sento before jumping in the vortex.

 **I have many thing to say. First, English is not my first language so sorry if my English is not perfect. Second, it's my first story ever so please be understanding and you have remark about my work, please review to give me advice, but please no flame. I hope you'll have a good time anyway.**

 **Next time : Sento arrive in a new world, but not like he hoped. Meanwhile, a cat found a strange bottle and a fated meeting will happen.**


	2. Chapter 2 : Unknown and excitement

**I don't own Fairy Tail or Kamen rider Build.**

 **Chapter 2 : A world of unknows and excitement**

/- Near Hargeon -/

Pain. It seems to be the only thing Sento Kiryu could feel right now. He could easily guess that he was on the ground, a mossy one at that. He could feel it at touch, as it was the only one of his 5 senses that seems to be working at the moment. He got up with difficulty, trying to straighten himself before opening his eyes. When he had finally stand up completely, he immediately notices something weird around him : he was no biologist, but he was intelligent enough to know that half of the plant around him seems to be out of this world, or out of HIS, to be more precise.

Finding his bag a few meters away, he noticed that his bag was open, and seems pretty empty. Rushing to it, he looked inside and found : his Build Driver, his Build Phone, the Rabbit Fullbottle, the Tank, the Lion and….

Nothing else.

\- "WHERE ARE THE OTHER FULLBOTTLES ?!", he shouted "MY SPARKLING BOTTLE ? MY HAZARD TRIGGER ?"

Sento start to feel bad. He was in this world since less than 2 minutes, and he has already lost 98 % of his possessions.

\- "This sucks.", moaned Sento. _In the other hand, seeing how I arrived, it was to be expected._

Indeed, when Sento jumped in the portal, there was 2 things he didn't think of. First, the fact that going through this portal would be the same as being stuck inside a washing machine. Second, the exit. He was literaly expeled of the portal like a bullet out of a gun. And of course, the exit was high in the sky. With everything, the fact that his bag opened and scattered his content across this place. So now, he had 2 missions : find Shocker AND find all his scattered devices.

\- "What a nice start.", said Sento in a sour tone.

Deciding not to let himself be defeated, he straightened himself and saw a port city quite close to him.

\- "Well, I have to start somewhere", he said before going to the city.

/- Hargeon Train Station-/

\- "E-Excuse me, sir ? A-are you okay ?"

It was a train controller. He was speaking to a young who, obviously, was in a bad shape. Dressed with some large white pants and an open vest, revealing a tone and slim body, this salmon haired guys, named Natsu, was sprawled on the ground, sickly pale and breathing heavily.

\- "Aye. It happens all the time.", answered Happy, a blue talking cat.

\- "Impossible, I'll never ride a train, ever again.", said Natsu while getting up… before turning to the window, feeling nauseated again.

\- "Let's go. If the info we got is correct, Salamander should be in this town.", declared Happy while getting off the train… forgetting Natsu inside when the train started to leave the station, taking him along.

\- "Ah… it departed already." Happy just said, watching it leave. "Hum ? What is that ? "

His eyes were laid on something, just outside the station near the rail. It was a really small bottle, white and kinda transparent, with some kind of design on it. It has a small cap, with the letter H on a white background and a S on a red one. Finding this thing kinda cool, he put it in his bundle and take off to get Natsu.

/- Hargeon's streets -/

\- "Tch, he only gave me a 1000 jewels discount." Complained a blonde haired girl with brown eyes named Lucy. "IS MY SEX APPEAL ONLY WORTH 1000 JEWELS !? »

She just had bought the silver key of the canis minor constellation, and her attempt to seduce the seller didn't worked as much as she hoped.

The young mage then noticed a large crowd of girl forming on the other side of the street.

-" Hum, what is happening over there ?", she asked herself

\- "A famous mage is in town ! It's Salamander-sama ! ", she heard some girls running beside her.

\- "Salamander ?", she repeated before beginning to smile widely. "You mean the mage who control a kind of fire magic that you can't learn in books ? I wonder if he looks cool."

Having said that, she started to approach the crowd. When she was faced with Salamander, she started to feel her heart beat faster and the heat rise to her face.

\- "W-What is happening to me ?", she asked herself.

Like drawn by some kind of invisible force, she then started to approach him when …

\- "IGNEEL ! "

Lucy instantly snapped out of her "trance". Natsu, who just came back from his second train ride, had jumped out of the crowd, searching for Salamander. But when his eyes met Salamander's…

\- "Who are you ?", he simply asked.

He then leaved, not even letting Salamander introducing himself, which made the fangirls catch him, dragging him back to excuse himself to their idol, who instantly calmed down when Salamander asked them to, making them swoon at him, right in front of a Lucy, who grew more and more suspicious. Salamander finally leaved, using a cloud made of some kind of crimson fire to fly away.

\- " What is he ? ", asked Natsu to no one in particular.

\- "He is really disgusting. ", ansxered Lucy, forcing Natsu and Happy to turn to her. "Thanks for earlier."

/- In a restaurant -/

\- "Yhurr ah naiz burrzon. (You're a nice person )" said Natsu while engulfing inhuman quantities of food.

\- "Ah ah, so you're Natsu and Happy, right ?", said Lucy, being splashed with sauce, thank to the way the two were eating. "I understand you, so just eat slowly."

\- "That Salamander guy was using magic called charm.", explained Lucy. "It's a magic that attracts other people's heart to the caster and it was banned many years ago. But trying to get girls attention by using this magic… How disgusting. Though, thanks to you, charm on me wore off."

\- " I see ", simply said Natsu

\- "I may not look like this, but I'm a mage, too.", she continued, the other two not really listening. "I'm not a member of any guild yet, though. A guild is an association for mages where they manage jobs and information for mages. But there is so many guild all over the world~, and it's hard to get into the popular one. Many great mages will gather in the one I want to get into."

At this point she seems lost in her own world, not noticing Natsu and Happy who were looking at her like she had 2 heads.

\- "Ahh what should I do !?", she continued. "I want to get in, but I bet It'll be hard… Ah sorry, you wouldn't understand a story from the world of mages, would you ?"

She stooped herself and said, calmly this time.

\- "But I'll surely join that guild. I bet I can get many big jobs there."

\- "I.. I see…", said Natsu, still shocked by Lucy's monologue

\- "You talk a lot", said Happy aboveboard.

\- "By the way ", said Lucy, ", aren't you guys looking for someone ?"

\- "Aye. It's Igneel."

\- "I heard that Salamander is coming to this town.", explained Natsu "So we came, but it was the wrong person."

\- "This salamander didn't look look a salamander.", noticed Happy

\- "How could…a human look like a salamander ?", questioned Lucy, clearly not understanding.

\- "Hrm ? Igneel is not human.", answered Natsu like it was normal. "Igneel is a real dragon."

Lucy reacted in a pretty normal way, considering what she just heard : she flipped out, eyes bugging out of her head and jaw falling.

\- "THERE'S NO WAY SUCH A THING WOULD BE IN THIS TOWN !", shouted Lucy, and judging by their reaction, Natsu and Happy just realized something. "HEEY ! DON'T TELL ME YOU ONLY JUST NOTICED !"

Calming down, she stood up, ready to leave, but not without leaving a little money to them.

\- "I guess I better get going… but go ahead and take your time."

Seeing her actions, Natsu and Happy, tears in their eyes, threw themselves on the ground and start bowing to Lucy, embarrassing her. Then Happy got an idea. He took the strange bottle out of his bag and gave it her.

\- "Here, it's to repay you for your kindness.", ha said handing the bottle.

\- "Hum, thank, i guess.", she said. As she leave the restaurant, she looked at the bottle. _This might be a rare magic item, i've never seen anything like this before_. She thought. _Well they were nice, kinda, so I'll keep it to remember them I guess_. With that, she smiled and walked away.

/- Timeskip. Evening. Hargeon's streets -/

\- "It sucks."

That was basically all that Sento was saying for the whole day he was in Hargeon. It's not that everything was bad : people were talking in the same language and the food and beverage (offered by some kind people) while being strange, were really good. But that was it for the good point. He had no money, or at least nothing usable in this world, so he couldn't buy anything. He tried to understand how this world was working, if there was a president, king or anything like that but he wasn't a big fan of politics and was completely lost. But what bring him down the most was the fact that this world was not a world of science or technology like he hoped, but a world of magic. He, Sento Kiryu, the greatest genius ever (according to him), was stuck in a world were his knowledge is unusable. Now that it was night-time, he was starting to think that he will have to sleep outside.

\- "If only I had brought a tent or something.", he complained.

Having reached the coast, he sat down on the sand and stared, not knowing what to do, a position he never experienced before since he always had a plan for something. That when he saw something, a boat who was heading to the beach he sat on at great speed, propelled by a giant wave.

\- "…Wait ? WHAT !?", he realized just before running to put himself to safety when.

*CRAAAACC*

The boat landed in a deafening crash on the sand, getting the attention of everyone in the city. Sento watched the boat and saw something that made him go wide eyed : a mermaid, carrying some sort of vase, before disappearing in sparkles of light.

\- "What the hell was that ?", he asked to himself.

He looked again at the boat. His hero's instinct asking him to go check if someone need help, and so he go to the boat. Using the Rabbit Fullbottle power, he climbed the boat and head straight to the cabin. He just had time to look inside when he saw a man throwing fire to a younger man, setting him on fire.

\- "Natsu !", a girl shout but was held back by a blue cat with wings

 _A blue flying cat_ , thought Sento, _well I just saw a mermaid so why not. But I have to help this guy_.

\- "Awful."

Hearing this single word, everybody stop and turned… to the burning guy who was standing like he was perfectly fine. And he was.

\- "What is it ? Are you really a fire mage ?", asked Natsu. "I've never tasted such awful 'fire'."

Much to the shock of Sento, that was actually EATING the fire. " _What kind of monster his this guy ?"_ thought Sento, _"is that how magic work here ?"_ Turning his head he saw that everyone was as shocked as he was. _"Apparently not."_ He deduced.

Just after eating this fire, Sento saw Natsu taking a big inspiration while pulling his head back and knew that something bad was coming.

\- "Bora-san ! I've seen him before !", said a thug to his boss. "Rosy hairt and scales-like scarf.. There's no doubt he his…the real."

He never finished his sentence since Natsu, putting his hand in front of his mouth had shouted, like a war cry.

 **\- "Karyuu no hokou !"**

And then, a stream of fire came out of his mouth, destroying the room and knocking out all the thugs, except the boss, who seems ready to piss himself.

\- "…The real Salamander." Concluded Lucy.

Then, after knocking down the boss, Natsu kept knocking bad guys after bad guys. Sento was captivated by the way Natsu was fighting, but he then heard the end of Happy's explication about Natsu's power.

\- "Dragon slayer ! Igneel taught Natsu this.", he finished

\- "It's weird that a dragon taught someone a dragon interception magic, isn't it ?", said Lucy and seeing Happy's face, continued, "But you didn't doubt it at all, huh?"

" _A dragon taught someone how to kill a dragon ? With every seconds that passes, I'm sinking in weirdness here."_

He looked again at Natsu and immediately noticed something : he had beaten everyone, but destroyed half the port while doing it.

"Does he even know how to restrain himself?", he said to himself

But then, the boss, Bora or something like that, stood up, rushed to Lucy and took her in a strangle hold, taking her hostage. Lucy started to fight back and Sento was ready to jump in but he then saw something strange, but also familiar. Some kind of whitish energy came out her bag, covered her back and then…

*SHING*

Needles came out of that energy, piercing Bora. It doesn't killed him, but let go of Lucy with a cry of pain. Bora then tried to run away, but Sento, sensing that this guys wasn't a beginner in the bad guy world, knew he had to jump in now. _"This girl, she just used Harinezumi ? Well, for the moment I have to catch that guy. How can I call myself a Kamen Rider if I let that guy leave, I already let to many things happen."_

He took out the Rabbit Fullbottle, shook it and, harnessing the power from the bottle, rush at a blinding speed to Bora, knocking him out in an instant.

But then, he saw some kind of army coming his way. Normally, seeing law enforcer wouldn't be a problem for a hero like him, but he saw that the blonde girl, the pink haired guys and the blue cat were fleeing the scene. He then remember that this girl had the Harinezumi Fullbottle, so he had to follow her to get it back, but he also realized something that made his hair rise up in excitation and a wide grin cover his face : if a girl with magic power could harness the power of the Fullbottles, then there have to be a way to understand magic by approaching it like a science. Excited by all the possibilities it could bring, and the ways it could help him in his mission of finding Shocker and his lost equipement, he then bring out his Build Phone, put the Lion Fullbottle inside to form the Machine Builder and speed out to follow the three mages.

 **So, second chapter done ! I hope you'll like it. As I said in the first chapter, it's my first story and I'm kind of building it on the moment. SO if you have any advice or remark, please review to help me. In the next chapter : Sento met up with Natsu and Lucy. The Rider enter the guild. Will they help him ? And where is Shocker exactly ?**


	3. Chapter 3 : Fairies and Rider

**I don't own Fairy Tail or Kamen rider Build.**

 **Chapter 3 : The Rider and the Fairies**

 _Italic : Sento's though_

/- Hargeon Train Station -/

Lucy, Natsu and Happy had managed to get away form the guards after destroying half of the port and were ready to get aboard. That is, if Natsu stopped behaving like a child.

\- "I don't wanna get into this demon !", cried Natsu, clinging to a column like a child to his mom on the first day of school.

\- "Stop being so childish and grow up !" shouted Lucy while pulling on him with all the strength she could gather. "If we don't leave soon, the guards are going to find us again."

\- "… couple quarrel", simply said Happy

\- "ABSOLUTELY NOT !", shouted Lucy while leaving Natsu to pull on Happy whiskers, her face as red as a tomato field.

*vvvvrrrrrrrrRRRRRRRRRMMMMM*

A rumbling noise catch their attention as they turned to see a man riding some sort of machine with two wheel. He stopped in front of them, got off his strange vehicle and pulled off his helmet. Taking it off, Lucy immediately recognized him.

\- "Hey ! You are the one who stopped Bora at the port."

\- "Hello, let me introduce myself. My name is Sento Kiryu."

\- "I'm Lucy, and this guy over there is Natsu and the cat is Happy."

\- "Aye"

\- "He does seem happy, but does he have a name ?"

When Sento said this, Happy fall to his knees, tears swelling in his eyes.

\- "M-My name r-re-really is Ha-Happy." Cried the little cat.

\- "H-Ho, sorry. I didn't meant it like that", Sento said trying to comfort the talking cat.

\- "Oh it's alright, no problem", answered Happy, standing up in an instant, as if he never cried. _"What the hell ?"_

\- "Well, if I way, what do you want ?" asked Lucy.

\- "I would like to come with you, wherever you're going", asked Sento.

\- "Really ? You would like to join the guild ?" asked Natsu with a smile.

\- "Hm, I don't know if I'm going to join your guild, but I do need help and you seem pretty powerful.", said Sento with honesty.

\- "What kind of help ?", asked Lucy , who started to feel like Sento was hiding a lot of things.

\- "Do you have a boss, or something like that, at your guild ?", he answered with another question.

\- "Well, there is the master, why ?" said Natsu, wondering why that guy wanted to know about the old man.

\- "My story is kind of complicated and if I have to tell it, it will be in his presence."

\- "Well, fair enough I guess." Said Natsu, apparently convinced. "Welcome aboard !"

\- "Thank you"

\- "Well we have a problem hum Sento right ?", said Lucy

\- "Yeah that's me, but what's the problem ?", asked the physicist

\- "Natsu has motion sickness and refuse to get on the train.", answered Happy.

Sento, seeing the problem, tried to use his brain to find a solution. And he did.

\- "Hey Natsu, see that thing there ?" he said passing an arm on Natsu's shoulders, while pointing to his Machine Builder. "It's called a bike. It can go to two or three times the speed of that train." Natsu gulped hearing this. "It's also a lot more dangerous, jumping and trembling with every small rock it met." By now, Natsu was sweating bullet. "The guard are coming there and none of us want to end up in prison so we have to way to go : it's either the train, or the bike. So,", said Sento while going to his bike and putting his hand on the handle. "which one do you choose ?" and to finish the fire mage, Sento had his motorcycle accelerate, making the engine roar with power, making Natsu snap.

\- "THE TRAIN ! I TAKE THE TRAIN !"

And he ran to the train without any second though.

\- "Wow, good job, Sento." Said Happy

\- "Well? Amazing, right? Terrific, right? I'm a Genius, right?", said Sento, his ego inflated with Happy's compliment.

\- "Huh yeah." Said Lucy, kinda creeped out by his sudden behavior. "We should go meet Natsu before he change his mind about the train."

/- Magnolia -/

\- "Wah… it's huge"

They actually had reached Magnolia, the city where the guild of Fairy Tail had his HQ and yeah, it was huge. A huge white, red and green building with a big leave-shaped door and the name "Fairy Tail" on a sign above it.

\- "Welcome to Fairy Tail", said Happy, formalizing their arrival.

Inside, I looked more like a restaurant than anything else. There was table everywhere, people talking, eating, and drinking. There was also a bar and a signboard where people were discussing about what was on it. Natsu then enter the guild, running like a mad men.

\- "We're home !", he shout while running toward someone.

" _He probably have some friend to greet."_ He was proved wrong when Natsu jumped and slammed his feet in that someone's face. He kicked him so hard that he broke the table and made him flew through the hall.

\- "Bastard ! That info you gave me about Salamander was fake !"

" _Or he might have not know it was a fake.",_ taking mentally the defense of the poor guy Natsu had kicked

Soon, the whole place became a battlefield, with chairs and tables flying everywhere.

\- "Whoa. I really came to Fairy Tail", said Lucy with stars in her eyes

\- "I hope they aren't always like that." Mumbled Sento. "At least it can't be worse for a first impression."

It could and the arrival of an half naked black haired man proved it. He really was half naked, just wearing a boxer.

\- "Did you say that Natsu is back !?" he asked. "Hey.. Let's settle our fight from the other time, punk !"

\- "Gray, have you been walking around like that ?" asked a brown haired girl.

\- "Hack ! Shit !" It seemed like this Gray guy just realized that he was half naked _"Really ? You just realized ?"_

\- "Another one of those undignified guys…", continued the girl "…that I really hate", she finished before chugging down a full barrel of alcohol. _"And where is the dignity in that, if you mind telling me ?"_ , referring to her drinking and her attire : pants and swimsuit.

\- "Yapping in the middle of the day, you are not little kids you know …" this was said by a big man, with white hair and strong body. Clearly the kind of intimidating you wouldn't want to meet at night in the street. "So fight with fists to show your manhood !" he said…before being send flying in a few seconds "And he got owned." Noticed Sento.

\- "It's so noisy here.", said a young man with red hair and wearing glasses.

\- "Ah ! It's Loki, the top ranked 'Mage you want to have as your boyfriend"!

" _So in this world, they also this kind of useless crap they called magazine."_

Loki approached…. Two girls in his arms, making Lucy fall to the ground.

" _Image officially destroyed, I guess"_

\- "What is this place ? None of them are normal.", said Lucy, weeping on the ground.

\- "My, newcomers ?", said a sweet voice

Lucy and Sento turned to be face with a beautiful young woman, with long white hair and blue eyes, trait she shared with the flying giant from before.

\- "Mi-Mirajane !", asked Lucy before fangirling, "Kyaaah~ ! It's the real one~~~" then she remember the fight "D-Don't you have to stop them !?" she asked Mirajane

" _You said none of them are normal, but you don't seems to be normal either Lucy. In my world, you would diagnosed with Emotional and behavioral disorders."_

Mirajane turned to the fight with a smile.

\- "It happens all the time~. You don't have to worry about it."

\- "Really ? is it a good thing ?", asked Sento

\- "And besides …" she started before being hit in the head by a flying bottle, making her fall to the ground.

\- "Isn't it fun this way ?" asked Mirajane, blood coming out of her head but smiling like it was nothing.

"It's scary." Thought Sento and Lucy.

By now, the fighter began to gather their energy : it would take turn for the worse in an instant because if magic, became involved in the fight, the building might not stay intact. But then, a gigantic human (or was it a monster) appeared.

\- "Cut it out, you fools !" he roared

\- "He's humongous !" said Lucy, clearly afraid.

The arrival of this thing calmed everybody. What Mirajane said could explain it.

\- "My… you were there, master ?"

\- "Master ?!" said Lucy and Sento at the same time

Sento, who asked to talked to the master of the guild, wasn't so confident about it anymore. After stomping on Natsu, who didn't saw the master behind his back and kept boasting about having scared the other, the master turned to Lucy and Sento.

\- "Mu ? Newcomers ?" he asked.

\- "Y-Yes…" answered Lucy.

\- "Fnuuuu …."

The master seem to gather his strength making Lucy almost shit herself and Sento reach in his backpack to get a Fullbottle, just in case. But then the master shrunk, to the point were instead of a monster, stood a small old man, dressed with a vest and shoes a hat looking like.

\- "Nice to meet you", said Makarov

He then jumped straight to the second floor, hitting the guardrail in the process. He then addressed the crowd.

\- "You've done it again, fools." He scolded "Look at these documents I received from the council."

He then started listing all the thing that the different member of the guild were accused of : public indecency for Gray, assault of a VIP for Elfman the giant, Kana (the brown haired alcoholic) drank 15 barrel and sent the addition to the council, Loki flirted with one of the councilman's grand-daughter. But the worse was Natsu who, from what Sento heard, have destroyed countless places and building : church, townspeople houses, historical building, etc.

" _This guild seems to be a refuge for dangerous people. Natsu being the worst of them."_

\- "Guys … the council members are at me all the time…" The master sees ready to explode

\- "But … forget about them." He said while burning the papers from the council, shocking Lucy and Sento.

\- "The power to overcome reasoning Is born from reasoning." Said Makarov. "Magic is not a miracle. When the 'spirit' flow within us and the 'spirit' flow in nature connects, they will form an embodiment for the first time. You will need a string mentality and a lot of concentration for that. I mean, pouring all of your soul into whatever you do is the magic. If you keep worrying about the watchful eyes of the higherups, your magic won't improve. Do not fear the fools of the council."

\- "DO WHATEVER YOU THINK IS RIGHT ! THAT'S THE WAY OF THE FAIRY TAIL MAGES !" he shouted, causing a huge wave of cheering in the guild hall.

Sento smile at that speech. It seems like this guild philosophy was the kind of thing Kamen Rider were born to defend. He might find some good allies here.

/- Later -/

Lucy just received her guild mark, a pink one on her hand. Mirajane, the stamp still in her hand, turned to Sento.

\- "And you were would you like to have your mark ?"

\- "Sento don't know if he's gonna join us." Said Natsu form his table. "He want to talk to the master before."

At that, everyone stopped doing what they were doing and turned to Sento. Makarov then said :

\- "Very well. What do you want ?"

\- "I need help, but you'll have to hear my story first."

\- "Well go on, tell us about it".

Everybody turned to Sento who start explaining.

\- "I'm from another world. In my world, I'm known as Kamen Rider Build, one of the warrior who fight in the shadow to protect humanity."

\- "If you really are from another world, why are you here ?", asked Mirajane.

\- "I used some kind of portal to get there and find my enemies."

\- "Your enemies ? What do you mean ?" asked Gray.

\- "They called themselves Shocker. It's an evil organization who want to control our world. They used a portal to come here. Me and my friend still in my world we think that they came here to find weapon, power or even an army to fight us in our world. I've been sent to stop them."

\- "Ok but why should we help you ?" asked Makarov, frowning. "If they are just here to gather things, it's your problem. "

\- "And we are strong, probably the best guild of them all. Why should we need your help ?", said Natsu.

\- "It will also became YOUR problem if you don't help me or if you underestimate them. You might be strong, but so are they and they are growing stronger with each passing minutes." Said Sento, trying to prove his point. "And as I am right now, I can't fight them with my full power."

\- "Why's that ?" asked Loki

\- "I've lost most of my equipment when I came here. It was scattered and I have no idea where it could be."

\- "What kind of equipment ? What does it look like ?" questioned Happy

\- "Well there is the Sparkling Bottle, that look like some kind of blue and red can and the Hazard Trigger, that look like a red handle with a blue button on it." Said Sento, describing his gears the best he could. Now that he thought of it, the Best Match weapons were still with him at least. "But beside them, there are my Fullbottles."

\- "Your what ?" asked Lucy

\- "My Fullbottles, here what they looked like." Answered Sento before pulling out his Rabbit, Tank and Lion Fullbottles, putting them on the table before him.

\- "Hey ! I have one of those things ! ", spoke Lucy before pulling out the Harinezumi Fullbottle.

\- "Ah yes. I forgot that I gave it to you." Indicated Happy "I found it at Hargeon."

\- "Yes, that's one of the Fullbottles, can I have it back, please ?", asked Sento

\- "Of course."

Sento took the bottle and put it next to the other. He frowned.

\- "What ? Aren't you happy to get one back ?"

\- "I am. But I still have just 1 Best Match. AND Before you ask, ", continued Sento, seeing that someone was going to ask a question. "I'm going to explain to you what is a best match."

He pulled his Build Driver out and showed it to the other. Alas for his audience, Sento turned into full scientific :

\- " I can use this to transforms by inserting two Fullbottles into the Build Driver's Building Modules and plugging them into the Twin Fullbottle Slots. I then turns the Vortex Lever, a crank that generates power to the Vortex Charge energy core generator unit by turning the lever. This gives the Nitro Dynamo inside the Vortex Charge the momentum it needs to generate power for transformation and finishers. Larger amounts of energy can be generated by increasing the momentum of turning the Vortex Lever and rotation speed of the Vortex Charge."

He stopped there to look at the others and saw that they all seemed dead inside, or sleeping. With a cough, he made them snap out of their slumber and restart, but decided to put it simply this time.

\- "To transform into Kamen Rider Build, I need to plug 2 Fullbottles into this device : 1 Organic Bottle and 1 Inorganic." He said slowly. "There I have 3 Organic Bottles, Rabbit, Lion and Harinezumi, and just 1 Inorganic, Tank".

\- "So for the moment, you MUST use Tank to transform.", said Gray still trying to process everything.

\- "Because Tank is actually the only Inorganic I have, yes." Confirmed Sento. "And, If I can transform into Build using any pair of Organic and Inorganic Bottles, there are pairs that work better together. For example, Rabbit and Tank. That's a Best Match."

\- "Can we trust you ?" finally asked Makarov after a small silence.

Before he could answer, everybody heard a detonation in the city.

\- "What is that ?" asked Mirajane

Everybody in the guild exit the building and they saw a monster, looking like a mix between a gorilla and an eel, and he was followed by men wearing black suit. They attacked the townspeople and wrecked everything in their way.

\- "Yeah ! Come on ! " Shouted the gorilla. "Let them see and feel the power of Shocker !"

Sento was shocked : he didn't have to look for Shocker, they just showed themselves.

\- "Hey, Sento. Those are the Shocker you're supposed to find." Asked Makarov. "Then show us that you can be trusted".

Sento smiled and walked to the Shocker soldier. When the Goreel (Gorilla + Eel) saw Sento, he did a double-take. He then spoke to Sento.

\- "You ! What are you doing here ?"

\- "Kamen rider's job is to stop the like of you, wherever they are."

\- "You do know that you are alone here right ? One Rider against a full army, you'll never win."

\- "It doesn't matter if I fail. To protect something important...I will rise up as many times as necessary! That's the Build that we created ! And I'll protect this world as long as I'm here."

At that, all the present guild members smiled : apparently, Sento has a philosophy that was compatible with the guild.

\- "Then you'll die right now ! Attack ! "

The Shocker soldiers then rushed to Sento, who just put his Driver Belt on. He took the Rabbit and Tank Fullbottles and started to shake them, making some equations appearing out of his thin air, stopping Shocker and surprising the Fairies.

\- "Now, shall we begin the experiment ?" said Sento

He spun the caps of the bottles and put them in the Driver.

 _ **RABBIT ! TANK ! BEST MATCH !**_

He then took the lever and start turning it, making pipe comes out of the Driver forming armor halves before and behind Sento.

 _ **ARE YOU READY ?**_

\- "Henshin !"

Then, the two halves snap on Sento.

 _ **HAGANE NO MOONSAULT ! RABBITTANK ! YEAHHH !**_

Sento was now wearing an armor that was red on the left half of his face, his right arm and left leg, and blue on the other halves. The red legs seems to have some sort of spring on it, while the blue feet seems to have caterpillar, like a tank. Now transformed, Sento was ready to fight. He used his Rabbit power to jump straight to the Shocker soldiers, kicking one straight in the face, sending him back into the other, destroying three of them in one strike. He then kicked, punched his way into the group of Shockers, beating them one after the other. The Fairies were impressed by his performance and Sento decide to show them a little more. When he destroyed the last soldier, he turned to Goreel.

\- "And now, it's your turned to become my guinea pig."

\- "Don't get cocky because you beat those pawns, I'll destroy you !", shouted the monster before rushing to the bottle user

Sento then took the Rabbit Fullbottle out of his belt, and replaced it with Harinezumi.

 _ **HARINEZUMI ! TANK ! ARE YOU READY ?**_

\- "Build Up !"

His red part were replaced by a white one, with the left eye shaped like an hedgehog and his right fist covered in some sort of ball, covered in spikes. He rushed to Goreel and they started to fight. They kicked, punched, dodged but the other could see that Sento clearly was taking advantage, going through any opening he could find, dealing a lot of damage thanks to Harinezumi's spikes, that seems to grow each time he punched.

\- "So that's the true power of this bottle ?", said Lucy to no one in particular.

\- "Wait ? True power ? What do you mean ?", asked Elfman.

\- "When we were in Hargeon, I had this bottle with me when a guy took me hostage." She explained. "I tried to free myself and I don't know how, but the bottle emitted a white energy that took the shape of spikes and pierced the guy. The spiked had gone through him, but he still felt the damage."

\- "Does it mean that we could use those bottles ourselves ?". Proposed Kana

\- "We will have to ask him after that.", answered Makarov, "After all, looking at him and what he said, I think we can trust him." He finished, a smile on his face.

Back to the fight, Sento send a spiked punch straight to Goreel face, sending him away on his back. He then took out Harinezumi, and placed back Rabbit.

 _ **RABBIT ! TANK ! BEST MATCH ! ARE YOU READY ?**_ "Build Up !" _ **HAGANE NO MOONSAULT ! RABBITTANK ! YEAHHH !**_

\- "The law of victory is set!", said Sento

He then turned the lever on the right of his belt.

 _ **READY, GO ! VORTEX FINISH ! YEAHHH !**_

What followed surprised the Fairies. With that announcement, Sento dived underground, sending a white energy chart flying up to the surface with a dotted line restraining Goreel. He was then send leaping up to the top of the chart, and he start following the dotted line, his blue leg stretched, the caterpillar on his feet starting up and going at full speed. He gained speed and crash into Goreel, the strike so powerful the monster started to be covered by electric arcs and sparks.

\- "You won't win this time, Kamen Rider !", said Goreel as he was struggling to stay on his legs. "Once we had found what we want, your world will be doomed ! And there is nothing you can do to stop us !"

\- "If there is no way to succeed, I'll build one by myself."

With that, Sento turned his back to Goreel who then fell to the ground before exploding. Walking away from the explosion, Sento unmorphed and walk back to the guild, stopping on front of Makarov.

\- "So ? Did I proved myself ?"

\- "Oh yes you did, my boy.", said Makarov with a grin.

\- "So those guys seems to be looking for something.", said Gray, having heard what Goreel said.

\- "Yeah. I don't know what though", answered Sento

\- "Well, if they want something to help them conquer your world, there is a lot of thing they could use. ", said a small blue haired girl named Levy. "It won't be easy to find what exactly."

\- "Well, anyway, we wanted to ask you something.", asked a old smoking guy named Wakaba, "What made Lucy able to use your Fullbottles power ?"

Remembering what he saw in Hargeon, Sento replied.

\- "I don't know, but I'll find the reason. There might be common factor between your magic and my bottles."

\- "Well, all jokes aside, ", said Makarov. " you can count on us to help you, but there is one condition for us to help you ?"

\- "And that is … ?", asked Build

\- "To become a Fairy Tail member and protect this worlds citizen from every kind of threat. Do we have a deal ?", answered Makarov.

\- "Of course, I accept.", smiled Sento, making everybody smile too

Makarov then grinned before saying :

\- "Well then. Let me welcome you to Fairy Tail, Sento Kiryu !"

 **And that's it, third chapter finished. I have something to tell all of you regarding the reviews. I had a problem and there are some of them that I haven't seen, so if you published one before this chapter came, please post them again if you could. I should receive mail now.**

 **I hope you like the story so far. Just so you know, I'm building it little by little, with what come to my mind. I already have a pretty good idea of the main event, like the arrival of the different bottles and best matches. I'll follow the manga, so I'll pass over some things sometimes, but I'll focus on Natsu and Lucy. I'm also thinking of Shockers intervention. So if you have idea, I'll take them into consideration.**

 **Next time, in "When Science meet Magic" : The guild is a huge family, so let's go save one of us. A snowstorm, a monkey and a bull.**


	4. Chapter 4 : Gorilla in the snow

**I don't own Fairy Tail or Kamen rider Build.**

 **Chapter 4 : Gorilla in the snow**

 _Italic : Sento's though_

/- Magnolia – Fairy Tail Guild Hall -/

Sento entered the guild, pushing the big doors wide open. Like yesterday, the hall was full of noises : people talking, eating, choosing which job to take. _"Talking about yesterday, it was one hell of a day"_. He remember the meeting with Natsu and Lucy, the arrival to the guild and meeting everyone and that fight with Shocker.

Sento remembered the talk he had with that Goreel. It seems like Shocker are actually looking for something. And that kept Sento up all night, trying to guess what they were looking for exactly. It could be a weapon, but it could also be some kind of magic item or a spell. If that was the case, he'll need help seeing he doesn't know how this magic work, even if he knew that there was a way to look at it from a scientific point of view, he still couldn't find the common factor.

" _What could it be ? It has to be something existing in our 2 worlds but what ?"_

He keep thinking about it when he reached the bar. Here, he found Mirajane using some kind of stamp on Lucy's right hand.

"There ! Now you are a part of Fairy Tail.", said Mirajane with a smile

"So that's what it is." He could clearly see a pink Fairy Tail emblem on her hand, where Mira had used the stamp.

"Natsu~! Look~! She gave me the mark of Fairy Tail.", said Lucy, smiling and showing her hand to Natsu.

\- "Good for you, Luigi." Answered Natsu.

\- "It's Lucy !", shouted an angered blonde. _"Are you always like this, Natsu ?"_

\- "Where did you find such a cutey ? I envy you. I wonder if she'd join my team.", said one of the guild member, looking at Lucy with heart in his eyes. Natsu then got up.

\- "Where are you going, Natsu ?" asked a fellow member of the guild.

\- "Work, I got no money." He answered, even that was just part of the truth. He did had no money, but those guys were also starting to get on his nerves. _"Why do they have to make those kind of remarks ?"_ , he though " _I mean, what if she's cute ? She is, true, but it's not important. Wait. Why I'm thinking about that ? I don't care._ ". Little that Natsu know, he'll soon find that he does care and probably more than he could think.

Back with Sento, he sat at the bar and Mirajane came his way, the stamp in her hand, and a cute smile on her face. _"She totally is the type of girl that cause Shotaro to go full flirt mode."._ he thought with a small wind, thinking of his friend back in his world.

\- "Good morning, Sento".

\- "Good morning, Mirajane".

\- "I think it's time you get your mark, you too." She said, motioning to the stamp.

\- "Yeah. Well, I'll take it on my hand, like Lucy. In blue." He asked

\- "Ok~, gimme your hand"

With that she stamped his hand, leaving a blue mark on it. Looking at it, Sento heard a small voice, and turned his head. It was Romeo, the son of Macao, a member of the guild, and the boy was talking to the master, who was cross-legged on the bar.

\- "Is my daddy back yet ?" asked the small boy.

\- "You're annoying, Romeo." Said the master. "If you are the son of a mage, trust your father, be a good boy and wait for him at home."

\- "He said he'd come back in 3 days…" said Romeo with tears in his eyes. "But it's been a week since then…"

\- "Please, look for him ! I'm worried about him !", asked Romeo.

\- "No way ! Your dad is a mage ! We have no one here who can't take care of himself ! Go home and drink your milk or something !"

The boy stopped, before punching the master in the face and running away, crying. Sento felt bad for the boy, and he wasn't the only one.

\- "It's seem very strict around here." He said

\- "Master is like that, but he's worried about Macao, too.", answered Mirajane

*CRAK*

Some people turned to the noise : Natsu, his eyes shadowed, had just put the request he had picked on the board with so much power he broke it. He then leave without saying a single word.

\- "Master.. Natsu's gonna do something bad …", said Nab, a mage with a tribal look and skull around his waist and neck.

\- "I bet he's gonna do help Macao. Stupid kid…" said someone

\- "No one can decide what he should do." Said Makarov. "Just leave him alone."

Sento was still with Lucy, trying to understand what happened.

\- "Wh-What happened to him all of a sudden ?", asked Lucy.

\- "The same thing happened to Natsu." Responded Mirajane. "His father disappeared one day and never came back."

" _Natsu have lost his father ? Well he might have seen himself in Romeo. But what kind of man can left his kids behind ?"_

\- "Though by father, I meant foster father.", continued Mirajane before turning to the physicist and blonde to conclude. "And he's a dragon."

At that, Sento spat his drink out of surprise where Lucy simply fell to the ground.

\- "Na-Natsu was raised by a dragon ?", asked Lucy, not believing it.

\- "That dragon found him when he was little and he learned words, cultures and magic from him." Said the barmaid. "But one day he disappeared. And since that day, he kept looking for him, knowing he will see him again one day."

What she said touched Lucy and Sento, realizing all the hardship their pink haired friend had to go through.

\- "We, Mages of Fairy Tail…", she started again, getting our attention once again "… are all carrying something. Wounds, pain, suffering."

Sento could understand in a way. Almost all the Riders have gone through difficult time before becoming Riders, and he was no exception. If Natsu was ready to go to the end of the world just to make sure that his friend don't go through the same thing as him, then there's no way he was gonna let him go by himself. As he got up to follow Natsu, he was stopped by Makarov.

\- "You are going to follow him, isn't it ?"

\- "Yes, why ? Do you intend to stop me ?", asked Sento

\- "No, but I have something for you."

This shocked Sento. What could it be ? A magic item ? or a special mission ? It was neither. What Makarov showed him shocked him to his very core.

The Diamond Fullbottle.

\- "I found this thing behind the guild the other day." He explained. "I wanted to know if you were a good guy before giving it to you."

Sento thanked Makarov, a big smile on his faced and raced after Natsu.

/- Near Mount Hakobe -/

\- "… And so I'll visit Mira-san's house next time ~."

\- "Don't steal underwear, okay ?" advised Happy

\- "Who would do that !?", answered Lucy in a shout

" _A lot of people. In my world at least."_ , answered Sento in his head.

Lucy and him had joined with Happy and Natsu to save Macao and Lucy just resumed what Mira said to them at the guild.

\- "Why are you here, anyway ?", asked the cat, sitting.

\- "What ? Does it bother you ?" said Lucy.

\- "Yes, a lot"

" _As straightforward as ever, Happy"_ "I came because Natsu's story remember me of my friends, the other Riders. We all have lives of these kind, with hardship, loosing people we held close."

\- "I see, and you Lucy ?"

\- "Because it's a chance.", she said with stars around her. "I wanted to do something that'd help Fairy Tail."

" _She just want to raise her reputation, I'm sure."_ Thought the cat.

\- "But then, ", she continued, "transportation really doesn't go well with you, does it ?", she asked Natsu "I pity you" she said, Sento not knowing if she was crying or laughing, but if he had to guess, he'd choose the second option.

\- "Also, I need to find a place to live once I find Macao." She said

\- "You can live with Natsu and me." Proposed Happy

\- "If you're seriously saying that, I'll pull out your whiskers, little kitty." She answered, blushing a little _"Living with Natsu doesn't sound that bad aft.. Wait WHAT AM I SAYING ?!",_ she then shook her head to clear her mind, but the blush was still here.

" _I'll need a place too. But I'll need space for my research.",_ thought the Rider

Last night he slept at Gray's, but it won't work on the long term. And he won't be able to bear with Gray stripping habit 24/7. It's already bad that he stripped in the guild, but that guy stripped EVERYWHERE, and It was annoying as hell.

"I don't know what's worse : Gray's stripping habit or Ryuga's dumbness"

/- In another world -/

\- "Achoo !"

Ryuga, morphed into Cross-Z Charge, sneezed in a middle of a fight against some Shocker soldier.

\- "Who's talking shit about me ? Well Whatever"

 _ **SCRAP BREAK ! TWIN FINISH !**_

/- Mount Hakobe -/

Suddenly, they could feel the carriage stop. Natsu sprung immediately back to life. The driver then said :

\- "I'm sorry, we can't go any further like this."

They came out of the carriage, and saw that they were in a snowstorm, lost in the mountain.

\- "It's cold !" shouted Lucy, clearly not expecting this kind of weather.

\- "That's cause you are wearing so little", asked Natsu, who seemed perfectly fine.

\- "The same goes for you !" countered the frozen blonde

\- "Except that he is a fire mage. It's normal that cold don't bother him." Said Sento

Lucy turned to see Sento, wearing a thick brown coat.

\- "Where did you found that ?" she asked

\- "You know Lucy, before going somewhere, normal people tend to do a thing called : preparation." Answered Sento with a dead serious.

She turned to Natsu and snatch a blanket from his bag. She then pulled out her keys.

 _ **OPEN THE DOOR OF THE CLOCK : HOROLOGIUM**_

Just then, in a puff of smoke, appeared a clock with arms and a face. She then entered the clock and began speaking but the boys could only see her lips moving.

\- " ' I'll stay here ' , she said " Horologium spoke for her

\- "What did she come here for ?" asked Natsu

\- " ' Speaking about that, what kind of job did Macao came here for !? ' , she says"

\- "You came without even knowing ?" said Natsu, raising a brow. "To subdue the brutal monster, Balkan."

\- " ' I want to go home. ' she says"

\- "Well go ahead, says I.", countered Natsu

"… _What's that ? They looked like an old couple."_

Then, they started hearing noises and a silhouette, barely visible because of the raging storm, jumped to Natsu, trying to catch him.

\- "It's Balkan !" shouted Happy.

Balkan then rushed past Natsu, straight to Horologium and he looked at Lucy through the glass.

\- "A human woman ~ ", he said, before speeding off, Horologium, and Lucy, on his shoulder.

" _Is everybody in this world a pervert ?"_

He then followed Natsu and Happy, trying to catch up with Balkan. When they arrived to his 'home', Natsu rushed in, only to slip on the ice and end up upside down against a wall.

\- "Where is Macau ?" he asked "Where did you hide him ?"

"How can you be so sure that he hid him ?"

The monkey monster seems to understand him, asking him to come closer. He then asked Natsu to looked outside, which he did …. And pushed him, making him fall off the mountain.

"Really, Natsu ? Really ?"

Lucy, angered either by the Balkan perversion or Natsu and Macao disappearance, pulled out a golden key.

OPEN A DOOR TO THE GOLDEN BULL PALACE : TAURUS

Like Horologium, a creature come out in a puff of smoke. But it was far more impressive than the clock. It was a huge bull, full to the brim with muscles, wearing dark blue underpants, fingerless gloves and boots. He also had a gigantic axe on his back.

\- "Taurus, my most powerful stellar spirit will be your opponent ! You perverted monkey."

\- "Lucy ! You have nice boobs as always. Moo-re amazing than ever." Said Taurus, with heart in his eyes.

" _It's official. Everybody is a pervert in this world." Sighed the physicist._

\- "Oi ! Don't take my woman !" said Balkan

\- "Your woman ? That's a moo-st unforgivable remark."

\- "That's right Taurus ! Get him !"

\- "You should say 'my boobs' instead of 'my woman'.", continued Taurus, dead serious

\- "THAT'S NOT RIGHT !", shouted Lucy.

" _So much irrationality, my brain is dying"_

But then, when Taurus was charging, Natsu came back thanks to Happy and jumped kicking the beast in the face. But alas, he kicked Taurus, knocking the spirit out.

\- "I can't… take it no moo-re" said Taurus before fainting

\- "You weak—", she turned from Taurus to Natsu? "I was worrying about you so much and then you come and this to me !"

" _This looked like a confession. Does she even realized what she said ?"_

Before they could continue, the Balkan charged at them, but Natsu kicked him in the jaw with a fire kick. The beast got up, feeling mad, and something strange happened : he threw a punch but while he seemed to have punched in the air, a mass of brown energy in the form of a fist came to them, making them jump out of the way. That's when Sento saw it. Hanging form the neck of the beast, a small brown bottle seems to be the source of this strange force that he knew better than anyone else.

The Gorilla Fullbottle.

\- "Guys let me take care of this." He said while pulling out his driver and two bottles.

 _ **RABBIT ! TANK ! BEST MATCH ! ARE YOU READY ?**_ "Henshin !" _ **HAGANE NO MOONSAULT ! RABBITTANK ! YEAHHH !**_

Now morphed, he was hit by an attack he didn't expect : a axe slice. The Balkan was using Taurus's giant axe. While he was down, Natsu rushed to fight the Balkan but he was having a hard time between the axe and the Fullbottle power. So Sento decided that it was time to pull out the big gun. He then pulled his Drill Crusher, a kind of sword shaped like a drill with a black handle and a white trigger. He put the Rabbit Fullbottle inside and pressed the trigger.

 _ **READY, GO ! VORTEX BREAK !**_

The drill then start spinning at high speed, making a small tornado of energy appear on the weapon.

\- "Natsu, watch out !" shouted Sento

Natsu, still busy with the Balkan, had stopped the axe with his bare hands. He looked at Sento and, seeing his weapon charging, he increased the heat of his hand to melt the axe, catching a droplet of molten metal in his mouth, before spiting it out at Balkan. _"Can that guy be anymore crazy ?"_ thought Sento, who didn't wanted to know the kind of heat it would take to melt something that wasn't from this world. Then, Natsu jumped out of the way has Sento ran to the beast and slashed it across his chest, sending him back into the wall of the cave. Sento walked to the beast and took back the Fullbottle.

" _Great ! Now I have a new Best Match."_

But then, the beast started to get strange lines appear everywhere on his body. Then, in a puff of smoke, the Balkan became Macao.

\- "Wait, What ?"

\- "Oh so he was taken over by Balkan !" said Happy "It's a magic to take over the body."

But as soon as he finished explaining, the wall where Macao crumbled and Macao fell of the mountain. Natsu jumped to catch him, Happy caught Natsu, then Sento, unmorphed, and Lucy, caught Happy, but it wasn't enough. They were ready to fall when Taurus, now awake, came to help them.

\- "No moo-re worry." He said with a grin

\- "Taurus !", said Lucy

\- "Bull !". said Natsu with tears falling from his eyes

" _Well, at least we can count on him for this kind of situation."_ , thought Sento with a smile.

After pulling everyone back in the cave, they put Macao on the ground and start inspecting his wounds.

\- "It seems he was fighting severely before he was 'taken over'.", noticed Happy

\- "Judging by his current state, it kind of obvious." Answered Sento. Macao's body was covered in bruises, he was sweating bullet and his breath was heavy. But what seems to be the more dangerous, was a deep wound on his right side. "He is going to die if we don't stop the bleeding quickly."

Then Natsu, like always, did something really bold. He covered his hand in fire and pressed on Macao's wound, making the latter shout in pain.

\- "GWAAAH !"

\- "WHAT ARE YOU DOING ?!" asked Lucy panicking

\- "THIS IS ALL WE CAN DO NOW ! LIVE WITH IT, MACAO !" said Natsu loudly, ignoring Lucy's comment.

\- "I see.", Sento said, getting Lucy's attention. "He is cauterizing the wound."

\- "He what ?" asked the cat, not understanding the word.

\- "He is using fire to burn the wound and close it. It will stop the bleeding at least for a moment." Sento replied, wide eyed at Natsu's quick thinking. _"He is not the brightest one, but when needed, he can have some good ideas."_

\- "DON'T DIE ! ROMEO'S WAITING FOR YOU !", the pink haired boy said to the man, trying to motivate him.

Macao stopped shouting and fell back on the ground.

\- "Haa..Haa. Shit, what a shame.", said the mage, "I got… 19 of them, and was taken over by the 20th one… Gah !" he ended with a cry of pain.

\- "I understand but stop talking or your wound will reopen." Said Natsu.

What Macao said shocked Lucy. "There was more than one monkey ? And he took such a job alone ? Amazing … I'm really… No match for them…"

" _I'm impressed. Being able to take on so many monster by himself, in my world, he would have a great Hazard Level. But why would he take such a risky job ?"_

/- Back at Magnolia -/

Once Macao was healed, or at least enough to travel, they head back to Magnolia. Once there, they met with Romeo. Seeing his father, the young boy had tears swelling up in his eyes. They learned that Romeo's friend were mocking mages and Fairy Tail and he had asked his father to do something great because he didn't wanted to be mocked forever.

" _It all started because kids were mocking him ? Kids can really be worse than criminals sometimes."_

\- "I made you worry. Sorry." Said Macao; kneeling to hug his son.

\- "It's okay… I'm the son of a mage."

\- "When those brats tease you next time, ask them…" he pulled back to look at Romeo in the eyes. "…if their old man can defeat 19 monsters by himself ! Okay ?"

Smiling, Romeo then turned to the others.

"Natsu bro~ ! Happy~ ! Thanks !", he said before continuing "And .. Thanks to you too Lucy sis ! And you too, Sento !"

" _Fairy Tail is an outrageous and reckless guild that defies all notion of logic. But they are fun, heartwarming and kind. I guess it's not that bad if I feel like I like those guys."_

Sento then turned and head to the guild.

\- "Well, if I have to stay here for a long time, I better find some place to live, first." He said, leaving Romeo and his father.

 **Well and that is 4 ! I'll try to keep my stories on time, but since I'm working from 8h to 18h, I my miss the time, beside I have a life so don't be surprised if there is delay. But I'll try to publish a new chapter by week at least.**

 **Since I have a problem with reviews, I can't reply to them, even with my mail notification, I'll answered some here.**

 **nudistbeast** **: thank you ! And I have to work on it but yeah I think I can add Ryuga.**

 **reynardgautama** **: Thanks ! Since it's my first, it means a lot.**

 **FanFictionHunter** **: Sento HAVE Tank, so I don't really plan on making him use single bottle forms. I'll try to find way to make mages use the bottles like for Lucy in the first chapter but It won't be now since I have to introduce the reason why they can used them in the first place, and it won't be before Erigor so sorry, but it will come. Unless I find way before that. And you are right for KeyDragon and NaLu, I might one day used this relation (form Mire the Matchmaker).**

 **Next Time : A new place, a new contract, a new mission. How can Natsu be such a sadist ? Why so much jewel for a book ?**


	5. Chapter 5 : Contract and mission

**I don't own Fairy Tail or Kamen rider Build.**

 **Chapter 5 – Contract and mission**

 _Italic : Sento's though_

/- Sento's Appartement - Magnolia -/

Natsu and Happy were at a loss for words. They got to the guild earlier this morning and learned that Sento and Lucy got new places to live in. They had decided to visit them and had started with Sento, being the closest to the guild. When they got to the house, they broke in by taking the window but saw that Sento wasn't here. When they heard noises coming from the cellar, they got down the stairs and opened the door. What they saw shocked them.

There was paper everywhere : on the walls, on the tables, even on the floor. Each one of these paper were covered in some kind of gibberish, with number, letter and signs of all kind. Sento had his back turned to them, not noticing that there were people within the room. He tuft of his hair was standing up as he was scratching his head with one hand while he wrote on a board with the other hand at a blinding speed, while talking to himself with the same speed. He was spewing what seems like a bunch of nonsense to Natsu.

" _Energy equals mass times speed of light squared ? What is that ?"_ , he thought, hearing Sento talking so much Natsu though that he was gonna fall of exhaustion in the next seconds.

\- "I knew that he was weird, somehow. " said Happy

The blue cat voice reached Sento's ear and he turned to them.

\- "Eh ?", he then saw that it was Natsu and Happy. "Oh it's you. What are you doing here ?" he stopped "Wait. More importantly, how did you got there ?"

\- "We wanted to see where you lived. Mira gave us the address." Answered Natsu, ignoring the second question. "What are you doing here ? What with all those … symbols ?" he said, gesturing to the papers.

\- "It's called an equation. It's used in all kind of science in my world. I'm trying to find the common factor behind why you are able to use the Fullbottles powers."

\- "So you did all that ?" said Happy. "Wow, you sure are a…"

\- "Yes. Amazing, right? Terrific, right? I'm a Genius, right?" answered Sento, cutting off Happy, boasting about his intellect, quenching his thirst for compliment.

\- "… nerd. I was saying that you're a nerd." Rectified Happy but Sento didn't heard him, or at least he didn't seems to.

\- "Well, anyway. We came here because we are going to Lucy's place and we would like you to come with us."

Sento had a lot of question he needed to find answer to : why the mages could use the bottles, how could he open a door to his world , where is shocker, how could Kana's alcohol resistance be so high, how Gray could not realize he was stripping in public, and a lot more. But he had to admit that he needed a pause. He put his pen down, took his long vest and follow them outside, straight to Lucy's.

/- Lucy's place -/

The three boys were now in Lucy's main room and judging by the noise, she was in the bathroom. Sento found this place really cozy, then he saw Lucy's key, still on the door. He stopped, then realized what it meant. He got wide eyed.

" _How did we got in there ? Wait, HOW CAN I CAN'T REMEMBER ? Did Natsu made me break into Lucy's house ? I can't even remember ? What the hell is wrong with this place ?"_

Still trying to find what was wrong with this place (Lucy's room or this world, he didn't knew), he heard munching noises. He turned and saw Natsu on a couch, eating chips messily with Happy on the coffee table eating raw fish, fish bones everywhere.

" _Someone's gonna be mad."_

And she did. When she came out of the bathroom and saw Natsu and Happy in her room casually eating, she kicked in the face, taking the two of them in one spin before crushing them on the wall.

" _A spin kick, eh ?_ _I wonder if a Rider already tried a spinning Rider Kick before ?"_

While Lucy was shouting at Natsu and Happy for obvious reason, Sento noticed a stack of paper on a what looked like a desk. His curiosity, like always, got the best of him and he took the stack of paper to read it. But Lucy took them from him in an instant and judging by the way she clutch it to her chest, on her knees and on the verge of crying, it seems important to her.

\- "What is it ? It's making me curious ?" asked Sento.

\- "Who cares what is it !?" she said

\- "I am." Replied the physicist

\- "Anyway, go home already !" she demanded, ignoring Sento's answer

\- "Don't want to. We came here to visit you." Said Natsu with a smile

\- "You're so selfish !" she cried.

Later, Lucy was clothed and had served tea to the visitors. When he thought of Lucy's earlier behavior, it kind of reminded him of Misora when she couldn't sleep because there was too much noise in the room. _"How long has it been since I came here. I miss them"._ He then tried to get back into the conversation Lucy and Natsu had.

\- "How many stellar spirits do you have a contract with ?", asked Happy

\- "I have 6. I have 3 Silver Keys, common keys you can find in stores. I have Horologium the Clock, Crux the southern Cross and Lyra the Lyre. She said putting her keys on the table. "And then there are the Gold Keys, they are very rare and powerful. I have Taurus the Bull, Aquarius the Water Bearer and Cancer the Crab."

Sento remembered that Gentaro, Kamen Rider Fourze, had fought against monster made out of the constellations. _"I wonder how he would react if he saw those ?"._

\- "The crab ! ? Crabs !? Craaaabs !"

\- "They get so excited over the most random things." She sighed

" _I have a feeling they are thinking about food. Can they even think about anything else ?"_

\- "Now that I think about it, I still have to make a contract with the spirit I bought at Hargeon. Perfect, I'll show you." Sha said going to make the contract.

\- "Does it have to involved seals ?" asked Happy with a little fear in his voices.

\- "Butt seals ? That sounds painful."

" _Natsu, I beg you, buy yourself a brain."_

Lucy took the Silver Key and goes to the center of the room. Natsu and Happy looked carefully while Sento, curious about seeing the making of that kind of contract, took out a notepad.

\- "I am the person who connects the road to the stellar spirit world. Thou…shalt respond to the calling and pass through the gate."

Then a light formed at the tip of the key, forming a lock of light that grew bigger and bigger.

 _ **OPEN A DOOR TO THE CANIS MINOR, NICOLA !**_

Then, in a puff of smoke, came a small white humanoid creature, with a yellow cone-shaped nose.

\- "PUUUN"

Lucy seems happy, smiling with stars in her eyes. But for Natsu, Happy and Sento, it was another story.

\- "D-don't feel too bad." Said Natsu trying not to hurt her.

\- "IT'S NOT A FAILURE !" shouted the constellationist.

\- "Scientist, when trying to find something, work for years before achieving the result they want. You just have to keep working and one day, you'll succeed. " completed Sento

\- "WHAT DID I JUST SAID ?" she shouted before calming "Well, let's get on with the contract

And it didn't happen like the boys expected. Basically, she just asked when she could call him, the white spirit shaking is head depending on what his response was. And in less than a minute, it was done. For the boys, it clearly was anti-climactic.

\- "I know it look easy but it's important." Said Lucy. "Stellar spirit mages regards contracts, meaning promises, with utmost importance." she said with confidence. "That is why I'll never ever break promises. Now come here Plue." The stellar spirit goes straight to her.

\- "Plue ? I thought it was Nicola ?" asked Sento

\- "Nicola is a generic name, he need another one."

Then Plue start moving in a strange way, as if to say something.

" _What's that ? As if we could understand ? I don't and I have an IQ of more than 600."_

\- "Plue ! That's a great idea !", said Natsu

\- "HE UNDERSTOOD IT ?!" shouted Lucy and Sento in surprise.

\- "I agree with Plue. Let's make a team ! "He then said smiling broadly, turning to them.

\- "Hey, that's a good idea ! Sounds fun !" Lucy said

\- "Let's get to work then. I've already decided on a job."

\- "My, you're thinking way too fast~~~. " said Lucy almost swooning in the heat of the moment.

Sento wasn't so enthusiastic. Natsu seemed a tad bit overconfident. There was a something that have to go bad, the scientist felt it.

\- "Whoa ! 200.000 jewels to get a book !" said Lucy not believing her eyes

\- "Right !? Isn't it an easy job ?"

" _Yeah, too easy if you asked me. There is something wrong with this quest. And why do I feel that Natsu didn't picked it just for that ?"_

He was right, and it was confirmed by what Lucy said next.

\- "The duke of Evaroo is a womanizer and a pervert. He is actually looking for a blonde haired maid." She read, starting to shiver and sweating bullet.

\- "Were you planning this from the beginning … ?" she asked, probably already knowing the answer.

\- "So stellar spirit mages value contracts. Very admirable, indeed."

\- "YOU TRICKED MEEEEEE !" cried Lucy, tears flowing out of her eyes. Sento was dumbstruck. Not moving trying to process what could be described as a genius plan, coming out of Natsu out of all people.

" _Did Natsu really thought of this plan ? He planned to trick Lucy all along ? He even used her own rule of not breaking promises against her. Natsu, you are one hell of a sadist."_

/- Meanwhile, at the Guild Hall -/

\- "Hrm ? The job at Evaroo Mansion for 200.000 Jewels… Did someone take it ?", asked Levy in front of the request board with her teammates Jet and Droy by her sides

\- "Yes… Natsu said he'll ask Lucy to go with him." Answered Mirajane.

\- "I was thinking about it, too …" sighed the petite woman, clearly disappointed.

\- "Levy… Maybe it's for the best that you didn't go." Said Makarov, like always cross-legged on the counter. "The client got in touch with me, he raised the reward to 2.000.000 Jewels." He said with a grin.

\- "2 MILLION JEWELS FOR A BOOK ?", shouted the guild, no one believing his ears. How could a job apparently so easy could cost so much ?

In a corner of the guild, a shirtless smoking Gray lifted his head, grinning.

\- "It's getting interesting."

/- Back with Natsu and the others -/

\- "How are you feeling on the carriage, master ?", said Lucy to Natsu.

Now that they were on their way to meet with their client, Lucy was taking a little revenge, playing her role of maid, a mean expression on her face as she was talking to a nauseous Natsu. Happy was not amused, saying he was roleplaying as her master. But she obviously didn't what to be the maid of a cat and certainly not Happy.

Sento was looking through the window, his mind working on why that job was so well paid. 200.000 Jewels just to take a book from a mansion, there was clearly something fishy in this. Was the Duke of Evaroo a powerful mage ? or maybe his mansion is some kind of highly secured stronghold ? While he was thinking about this, they arrived at the village where their client lived.

/- Later -/

Sento, Natsu and Happy were eating at a restaurant, waiting for Lucy to come back since she left them to check out the town when they arrived. Now, Sento was drinking coffee while watching Natsu and Happy talk about Lucy's share of food.

\- "Let's keep the oily one for Lucy. " proposed Natsu. "She does look like she loves oily stuff."

" _I just give up, I can't understand how your brain work, Natsu. How could you know if like that kind of food or not ? "_

\- "Since when do I love oily food … ?" sighed a well-known voice.

\- "Oh! Lu…cy ?"

\- "How is your meal, sir ?" asked Lucy, now clad in a really cute maid outfit that fit her like glove. She even put her hair in two ponytails. Sento was surprised, but didn't react that much but that wasn't the case for Natsu and Happy, who seemed dumbstruck. But what nobody saw was the small blush on Natsu's face seeing Lucy. But he seemed to get back to his senses and, finishing eating, they made their way to their client house. For strange, they were asked to go through the back door. Once inside, they were greet by their client, a man called Kaby Melon. In the living room, they sat down to discuss about the job. But Lucy's mind was blocked on the client and the city name. "Melon… this town's name too… I've heard them before…".

\- "So here's the job. I want you to go to take a book named 'Day Break' form the Duke of Evaroo's mansion and destroy it !"

\- "That's strange." Said Sento. "Why would you pay 200.000 just to get a book destroyed ?"

\- "For the fees, it's not 200.000 anymore, it's 2.000.000." Said Kaby

\- "2 MILLIONS !?"

While Lucy, Natsu and Happy were trying to come to term with the sharing (Happy trying to get Lucy a share of 0), Sento brain was working at top speed.

" _2.000.000 Jewels to destroy a book ? Ok now I'm sure about it : there is something that this guy is not telling us. And it have to be something deep."_

\- "That book have to be destroyed. I can't forgive this book's existence."

After that, Natsu, completely fired up (quite literally since in WAS on fire), took off with Sento in one hand and Lucy in the other.

"Wait? What does he mean by he can't forgive this book existence ?"

/- Later, Evaroo's Mansion -/

\- "Excuse me, I came for the blond-haired maid position."

Lucy, in her maid outfit, was in front of the mansion, trying to sneak inside. Natsu, Happy and Sento were a little in the back, looking at her.

" _Fu Fu… It's easy. All I have to do is become the duke's favorite. Then I'll find the book, burn it and get the 2 million" she snickered in her mind._

Just then, the ground near her started to swell and something jumped out of the ground. It was a maid, but she looked more like a gorilla than a maid.

"There's a girl who came for the position, master !" she said into the hole, with a deep voice matching her appearance.

Then, out of the hole, the duke of Evaroo appeared. He walked to Lucy, he checked her out then turned before saying :

\- "Rejected ! Go home, ugly." Lucy's pride just took a huge hit, not understanding why this guy rejected her. The answer came when 4 silhouettes jumped out of the ground.

\- "For someone as greaaaat as I am, " said Evaroo. "Only beautiful girls would suit me, boyoyoyoyo."

The four new maid were as ugly as the first one, explaining why Lucy was rejected : that duke's sense of beauty was completely messed up.

/- Later -/

Lucy, back in her normal clothes, sat against a tree, crying over her broken pride.

\- "You're useless." Said Natsu, with no tact

\- "It's not that ! It's that his sense of beauty is retarded ! " countered Lucy with tears falling out of her eyes.

\- "An excuse." Casually said Happy

\- "Kieeee ! How vexing !"

\- "Well it look like we'll have to go straight in, his time." Said Sento.

\- "You read my mind, partner ! Let's go !" said Natsu, cracking his knuckles

\- "I'll never forgive this pervert ! " said Lucy, still crying, but probably out of rage toward the Duke.

Meanwhile, inside Evaroo's study, the Duke was sitting in some kind of throne with 3 man behind him.

\- "Mages keep coming even with all the failures ? Oh well, how should I kill them this time ? Boyoyoyoyo ! "

\- "Like you did until then : " Said one of the men, reaching for his pocket. "By leaving it to us." Smiled the man, looking at what was in his hand, finding a small gray bottle with a gun barrel on it.

The Gatling Fullbottle.

 **Ok, 5** **th** **chapter ok. I now that it might be fast for you, but the ideas are coming and I'm afraid that if I stop, I won't be able to continue. I just hope that you like the story so far and I welcome you to leave a review or even send me a PM to give me advice or other remarks. After all, don't forget it's my first story ever.**

 **Next Time : The book, protected by mercenaries, written in pain, hiding a secret. Spiked whip, diamond rain and frying pan.**


	6. Chapter 6 - Day Break's secret

**OK here's the 6** **th** **chapter. Before starting, I need you all to know that my reviews are working again, so I'll be able to see them without any problem now. Now, I'll answer to some of them :**

 **FanFictionHunter : I don't think that Sento will extract magic essence in my story, sorry. I already have a pretty good idea of where I'm heading so it would be hard to had big changes, but if they are interesting, I'll try.**

 **Perseus12 : Thanks, glad you are enjoying it !**

 **Ridertwinmitsuru : If I switched the story to English, it's for many reason, but there is a really important one. It's a Kamen Rider x Fairy Tail crossover story, and judging by the Traffic Graph, more than half of the viewer are from English speaking country. It's a specific niche with almost no French, so if I want to write this story, I had to change the language. It's not because I wanted attention, if that was the case, I would be writing in a more 'popular' section like Naruto for example.**

 **Also I realized that I've never done any disclaimer until then. I'll update my previous chapters to had one. So I don't own Fairy Tail or Kamen rider Build.**

 **Anyway, let's go !**

 **Chapter 6 - Day Break's secret**

/- Evaroo's mansion, on the roof -/

After Lucy's rejection from the Duke, the group had decide to sneak inside the mansion, to take the book and leaving without being noticed. On the roof, Natsu used his heat to melt the window and open it from inside, allowing them to come in. They were now in some kind of attic, or at least a big closet, where was stored scrolls, furniture, crates, even some piece of armor. Happy even found a skull that he wore as a helmet, making him really creepy. Among those thing, a strange globe with a wolf on it, shined, reflecting the image of the 4 partners. After checking that no one was outside, they left the room and began to search the book.

\- "Hey, Lucy.", asked Natsu. "Don't tell me we are gonna check room after room like this ?"

\- "We are !" she confirmed, "We'll just find the book without getting noticed. Doesn't it sound cool ? Just like a ninja." She said, trying to got them involved. Little did she know, they were gonna take that ninja thing a little too seriously.

Suddenly, the ground started to swell and the 5 ugly maid jumped out of the ground, the gorilla one leading the 4 other, who were armed with spears.

\- "UHOOOOOOOOOOOOO ! " shouted Natsu and Happy, the surprise of the latter making him lose the skull he still ha don his head.

\- "They found us !" said Sento, ready to take out his Driver.

Natsu then wrap his scarf around his head before fire-kicking the maids with his hands joined, while shouting "NINJAAAA !"

\- "We can't let them find us just yet. Nin Nin." Stated Natsu, imitating some sort of ninja with Happy playing along.

\- "You guys are so noisy though…" said Lucy, sweat dropping at the boy show.

Sento was looking at them too, and he was also thinking about ninja. To be more precise, he was thinking about his Ninjya Fullbottle and guessing how those two would behave if they learned about it.

" _When I'll get Ninjya back, I'll have to hide it from those two or they'll become unmanageable."_

Lucy, fearing that their encounter with the maids got the attention of someone, grabbed Natsu and dragged him into a room, closing the door by slamming it. _"So much for discretion, Lucy."._ They now were in a big room that looked like a library, with book stacked in shelves against the walls of the room. Hoping to find the book, they started to check the shelves. While looking for 'Day Break', Sento was thinking.

" _That duke look stupid for sure, but he have a lot of book. There is something I don't understand : Kaby Melon said he couldn't forgive this book existence, that mean he must have a deep connection with this book. Then why is it here ? Did the Duke steal it ? No, this doesn't add up. If he had that book at first, he could have destroyed it before. Does that mean that the book as always been the property of the Duke ? Then why can't Mr Melon forgive his existence ? There is one more unknow in this equation."_

While he was thinking, he could hear Natsu and Happy looking for the book in their own way : by talking loudly and stopping at every book they found intriguing.

\- "Ooooh ! I found a golden book !" said Natsu, a real golden book in his hands.

\- "LOOK FOR IT SERIOUSLY, WILL YOU !?" asked Lucy.

As they all turned to Natsu, they saw the title of the golden book he was holding : "Day Break". It shocked us : did we really found it so easily ? Natsu was ready to burn it when Lucy stopped him. Apparently, this book was written by a man named Kemu Zaleon, a mage that also was a writer and Lucy was a big fan of his work. Lucy, having entered her 'bookworm' mode, tried to talk Natsu into not burning the book, since she wanted to keep it. While she failed to make Natsu understand what she wanted, Sento was still blocked on the author name.

" _Kemu Zaleon ? Wait a second …"_

He couldn't finish what he was thinking, since they were all interrupted by a voice and cracking sounds.

\- "I see, I see. Boyoyoyoyoyo. So that's why you were after."

The duke then jumped out of the ground, like the maid in the hall.

\- "I'm glad to allow you guys to do whatever !" said the Duke. "I'm a genius, boyoyoyoyo."

\- No you're not. I am !", countered Sento immediately.

" _Why are you taking this so personally ?"_ thought the physicist's friends.

\- "I was wondering what the mages were looking for. And it was that worthless book." Said Evaroo landing on the floor.

" _Worthless ? Mr Melon would pay for 2.000.000 Jewels to destroy a book and he said it's worthless ? And Evaroo could be right. I mean, judging by the book he have, the Duke seems to know a lot about books. So why ?"_

\- "S-so can I keep it then ?" asked a hopeful Lucy

\- "No. Regardless of how worthless it is, the book still belongs to me." Stated Evaroo.

\- "All we have to do is burn it and we'll be done here." Said Natsu.

\- "No ! Absolutely not !" said the blonde, squeezing the book close to her.

\- "Lucy ! It's our job !" countered Natsu fully serious.

\- "Then at least let me read it !", she said before falling to her knees and starting to read.

\- "Here !?", asked all the mens in the room, shocked by Lucy's decision.

\- "Bull shit ! I don't like this ! How dare you touch the book that belong to the duke of Evaroo !?" seethed Evaroo. "Come, mercenaries !"

At that, the shelves started moving, revealing an hidden door. Out of it came three man.

\- "It's finally time for business." Said a man with black pants and white and green vest. He was bald except for a braid at the back of his head. He also had 4 kanjis on his faces and what looked like a giant frying pan on his back.

\- "if we get paid without doing actual work, mama will get mad at us." The second one was tall, with white pants and blue and yellow vest. His spiked hair were held by an orange headband.

\- "Good afternoon." The last one was blonde. He had a grey fedora, a white shirt with two gun in holsters strapped to his side. He also had jeans on. The three of them had the same mark : a wolf head on an S.

\- "They are from the mercenary guild, Southern Wolves." Explained Happy

\- "Boyoyoyoyo ! Southern Wolves are always hungry !" laughed Evaroo "Prepare to die !"

Tension was rising between the two groups. Except for one person.

\- "HEY !". All the man shouted at Lucy, still reading the book with glee, not paying any attention to the rest. This annoyed the Wolves greatly.

\- "What a joke. They claimed to be mages of Fairy Tail ?" said the wolf with the fedora.

\- "Vanish Brothers ! Don ! Retrieve the book at once ! And kill them !" ordered Evaroo.

Then, Lucy suddenly took off, asking Natsu and Sento to buy her some time.

\- "This book seems to hold some kind of secret ! I'll find out what it is !" she explained.

" _Lucy can be a genius when it comes to books. If she said there is a secret in it, it's probably true. Moreover, it could be the unknow I was looking for."_

\- "Lucy ! Take this !" Sento said, giving discreetly something to Lucy. The Harinezumi Fullbottle. "I still don't know how you did it, but if could harness that power once, you can do it again." She nodded and rushed out of the room.

\- "Change of plan ! I'll get her myself !" said Evaroo diving into the ground. "You three ! Obliterate those brats !"

\- "Happy can you go after Lucy ?" asked Natsu, stretching.

\- "The opponent is three Southern Wolfes ! I'll support you !" said the cat, worry for his friend written on his face.

\- "Don't worry Happy. I'll back him up." Said Sento

With that, Happy nodded and rushed to Lucy.

\- "Come on, flame mage." Said the bald one

\- "How do you know I'm a flame mage ?" asked Natsu

\- "We saw everything on the surveillance crystal." Continued the brothers. "The girl is a stellar spirit mage with 7 contracts. The cat use an ability type : "Wings" and as for you, you melted glass and wore flame on you legs. You are most likely a flame mage. But we don't know anything about your friend's magic." He concluded, pointing to Sento.

\- "You observed us well. That means you're prepared to end up charred, right ?" Natsu said, igniting his hand.

\- "Unfortunately, I must decline because flame mages are the easiest kind of opponent for me." Said the bald one, who pulled out his pan.

Then he rushed at the two, slamming his pan in Evaroo's desk. While they were in the air after dodging, Sento and Natsu were grabbed by the big guy who threw them at the with so much force they got through it and landed into the hall. The last one, the guy named Don, was just looking at how things were going. Once in the hall, the bald one asked them a question :

\- "Do you know the weak point of a mage ?"

\- "Can't handle transportation ?" answered immediately Natsu, wide eyed.

" _No, that is YOUR weak point Natsu. Isn't there medicine for that kind of thing in this world ?"_

\- "It's the body." He said. "You cannot learn magic without training your intellect and spirit." He continued, slamming the pan on the ground, Natsu dodging it.

\- "As a result…"said the big one, trying to punch Sento. "During the process of mastering magic, your body doesn't get enough training."

\- "Which means that you are no match for them in neither speed nor power." Concluded Don jumping out of the balcony.

\- "But then, none of your attack are hitting us." Taunted Natsu, Sento by his side.

\- "I see? Your speed seems to be good. You trained yourself somewhat." Admitted the bald.

\- "But you won't be able to beat us with our ultimate technique." Said the brothers in one voice.

\- "Here it come" said Don with a grin. "They are finished. Those Fairies are toasted."

\- "Let's go !"

 _ **HEAVEN AND EARTH EXTINCT SLAYING ATTACK !**_

The big one jumped on the pan and his brother then threw him in the air, making Sento and Natsu follow the movement.

\- "If you look up to the heavens, we are down here on earth !" said the bald, using the opening to strike them with his pan.

Salamander and Build looked at him but …

\- "I you look around on earth, we are up here in the heavens !", said the big one while striking them from above.

\- "This is the Vanish brother's united attack : Heaven and Earth extinct slaying attack ! " said Don. "No one ever survived after taking it."

But Natsu and Sento got up, seemingly bored.

\- "No one has survived… And ?" asked a sighing Natsu. "Oh well, just get blown away !"

 _ **KARYU NO HOKO !**_

Natsu unleashed his powerful fire attack, straight at the Vanish Brother. But that didn't seem to scare them.

\- "This is it." Said the bald one. "Anti flame mage user.. as well as an ultimate technique ! "

 _ **FLAME COOKING !**_

\- "My pan absorb flames, multiplies it's power and sends it right back !" he said, unleashing the boosted flame on Natsu.

" _Bad move."_

Indeed, Natsu, now covered in flame, came out of them and rushed to the Vanish Brothers, much to the shock of the brothers and Don.

\- "Didn't you hear me ? " he said before taking their faces in his hands. "JUST GET BLOWN AWAY !"

 _ **KARYU NO YOKUGEKI !**_

Natsu's set his hand ablaze, sending the brothers flying, knocked out. After that Natsu was really to go but was almost shot by a bullet. Don had drawn out his guns and shot one bullet to stop them. He seemed mad.

\- "So you beat them, uh ?" he sneered " If you want to leave, you'll to go through me."

\- "Come on, shoot at me. I'll just melt the bullet away. AHAHAHAH" taunted Natsu.

Don lower his gun a little, shooting at Natsu. But unlike what Natsu had planned, the bullet hit her mark and pierced Natsu's foot.

\- "You see, those are not real bullets. It's my magic." He explained, ignoring Natsu pain. "No matter what you do, I'll change them to beat you. There is just one downside with that, the shooting speed is not that great. But I recently found a way to avoid that inconvenient." He concluded, grinning before reaching into his pocket, taking out a small gray bottle.

\- "The Gatling Fullbottle !" recognized a wide eyed Sento.

\- "So that's what it's called ?", said the last wolf. "Well thanks to that 'Fullbottle' as you said…" he smiled pulling out his second gun. "… My shooting speed is far more convenient." At that, a gray energy seeped out of the bottle. That energy covered the gun and took the form of two big gatling gun. Don then fire his gun, causing a real shower of bullet to rain down on Sento and Natsu. Sento then took Natsu to safety behind a column.

\- "Stay there, I'll take care of this guy." Said the Rider.

Natsu nodded and Sento goes back to face down, who was waiting.

\- "So you want to do it one on one ? It doesn't matter, I'll win anyway." Said Don with clear confidence in himself.

Sento placed his Driver on his belt and start shaking 2 bottles, making equation appear in the air.

" _What the hell is that ? Wait, is it …"_ though the gunner, seeing the bottle who looked so much like his.

 _ **RABBIT ! TANK ! BEST MATCH ! ARE YOU READY ?**_ "Henshin !" _**HAGANE NO MOONSAULT ! RABBITTANK ! YEAHHHH !**_

\- "Oh ! So that his the real power of those things ?" said Dom, between shock and glee. "It will be a blast when I'll get it after beating you."

\- "Now, shall we begin the experiment ?", he said, now clad in his blue and red armor, ignoring the comment. Next, he rushed at Don, jumping above the bullets. He land next to him and tried to punch him, but it seemed that this guy was also skilled in close ranged fight, dodging Build while using every opening to shoot at the Rider.

" _It look like this guy don't have a big defense, so it won't take much to beat him. But he now how to dodge. And the real problem are those projectiles."_ He though _, trying to think of a way to win this. "Wait a second ? Those bullet aren't organic right ? In that case …"_

Landing a kick on Dom face, sending him back, Sento stood up, taking the Rabbit and Tank Fullbottles out of the Driver and took out two other : one brown, the other cyan. He shake them, then plugged them.

\- "The law of victory is set !"

 _ **GORILLA ! DIAMOND ! BEST MATCH !**_

Turning the lever, the essences from the bottles came out of the Driver to form the two halves of the armor on the Snap Ride Builder.

 _ **ARE YOU READY ?**_ "Build Up !" _ **KAGAYAKI NO DESTROYER ! GORILLAMOND ! YEAHHHH !**_

Now, Natsu saw the new form of Sento. Half of the armor was brown, the eyes shaped like a gorilla raising his arm. The most prominent feature of this form was his arm, which consisted in a huge fist. The other half, the cyan one, was based of diamond like the eye of this part suggested and the shoulder pad was shaped like a real diamond. Dom saw this and, without realizing it, started to tense.

\- "You think a fancy color swap is gonna make a difference !?" he shouted, before shooting again at the Rider.

Sento rushed to him and, to Natsu and Dom's shock, Sento raised his left arm and the bullet stopped, changing into diamond. Dom kept on shooting, hoping to get a result, but it didn't came and he took a direct hit from Sento's right fist.

He was sent back and as he was struggling to get up, Sento's turned the Driver lever once again. When Dom was up again, he unleashed a new volley of bullet, determined to beat Sento.

 _ **READY, GO ! VORTEX FINISH ! YEAHHHH !**_

Sento lift his left arm, the diamonds on it shining as the bullets changed into diamonds, forming a shield of some sort. After some time, namely when Dom understood that what he did had no effect and stopped shooting, Sento punched the diamond shield, shattering it and sending the shards flying at Dom with so much speed that you could only saw blue lines rushing at him. The impact was so violent Dom was sent flying into a wall, knocked out. Unmorphing, Sento got to pick up the Gatling Fullbottle that Dom let down.

" _Now I need Taka, and I'll have one of my favorite Best Match again."_

He walked to Natsu, who didn't seems to be that hurt.

\- "Is your foot ok ?" asked Sento, pointing to the wound.

\- "Yeah. It hurt but it's ok." He answered. "Now, shall I go look for Lucy ?"

\- "You mean 'Shall WE look', aren't you ?"

\- "Hum, y-yeah of course. My tongue slipped." rectified Natsu.

But as they were leaving, the gorilla maid stood up abruptly. Natsu and Sento saw it and rushed to put her down again but when they grabbed her, they saw bright lights that caused them to close their eyes. When they open them, they were in some kind of sewers, between Evaroo on one side, and Lucy on the other. Sento also saw a weird guy next to Lucy, with crab legs on his back, hair shaped like pliers and scissors in his hands. He then looked at the Duke and saw a golden key in his hands.

\- "Why are you with Virgo ?" he asked surprised, clearly not expecting them to be here.

Hearing the name Virgo and judging by the key, he understood. That maid was a stellar spirit and that guy had the same magic as Lucy. Sento jumped out to Lucy, who was still trying to assimilate the fact that we travelled through the stellar spirit world, which was normally impossible.

\- "What should I do ? Lucy !", asked Natsu still gripping onto Virgo.

\- "Get rid of her !" answered Lucy, pulling out her whip.

\- "All right !"

Natsu then kicked the spirit in the head while Lucy used her whip to get a hold of the Duke, sending him to Cancer who slashed him with his scissors. The attack made him bald and fall to the ground, but he still stood up. Lucy, deciding it was time to end it, choose to use something else. Taking out the Harinezumi Fullbottle Sento lent to her, she closed her eyes, trying to remember what she felt at Hargeon that helped her harnessing the power. She then felt it, the white energy seeping out of the bottle to cover the whip, covering it in spikes. She then whipped at the Duke, hitting him in the chest.

 _ **HEDGEHOG'S SPIKED WHIP !**_

Now, the Duke of Evaroo was down for good and the book retrieved, they head back to their client. Like Sento suspected, there was something with this book and Lucy was sure about it too. Once they reached their destination, it all was revealed.

If Kaby Melon wanted to destroy that book, it was because his father wrote this book 31 years ago for the Duke of Evaroo, who had locked Kemu Zaleon to make him write a story about himself. When he came back, his author pride broken because of what he had written, he had chop his arm off and commit suicide shortly after that.

\- "That's why I wanted to eliminate this piece of trash from the world. Only with this atonement can he regain his pride as a writer."

As he was about to burn the book, it shined brightly and floated in the air, the letter of the title reorganizing, changing from 'Day Break' to 'Dear Kaby'.

\- "Kemu Zaleon casted a spell that shuffled the characters in the book, including the content and everything else." Explained Lucy, as the book opened, letting the letters leave the pages, dancing in the air as they were changing places before going back in the book, forming a totally different content.

\- "Thank you." Said Kaby, tears falling from his eyes. "I can't burn this book."

\- "Then we don't need our reward, either." Said Natsu, grinning and surprising everyone. "We were here to destroy the book and we failed to accomplish that."

\- "N-No… But we can't do it that way…" said Kaby

\- "He's right… It's his generosity… Let's just accept it." Said Lucy, trying to make Natsu change his mind.

\- "You're so greedy !" Happy replied. "You were saying such good things, but now they've all gone down the drain."

\- "That's different ! " countered Lucy before turning to Sento. "Right, Sento ?"

\- "Well… I have to admit that Natsu have a point."

\- "I said we don't want it, so we don't want it." Concluded Natsu, applying his point of view to the group. "Let's get going. You should go back to your own house too, Kaby."

/- Later -/

As Natsu said, it was revealed that Kaby Melon wasn't rich and that the house belong to one of his friend. When they talked about Kemu Zaleon the writer, Lucy said :

\- "It seems like he was in a mage guild when he was young. He wrote stories about the adventures he experienced then. I yearn for him" she finished with a somewhat dreamy look in her eyes.

\- "I see. So that's what it was." Said Sento to himself before turning to Lucy "Those papers at your house, it's a story you are writing right."

\- "D-Don't tell anyone about it, okay !?" she begged

\- "Why not ?", asked Natsu

\- "I'm not good at it, yet ! It's embarrassing if someone reads it !"

\- "Don't worry, no one will read it." Said Happy without any consideration like always.

\- "THAT'D MAKE ME KIND OF SAD, TOO !"

"Well, it was quite interesting. And what's more, I have found the Gatling. I'm closing on one of my favorite Best Match. I hope I'll get Taka back soon."

Little did he know, he'll find it sooner than he though thanks to an armor wearing redhead, coming closer to Magnolia.

 **Ok, so it's done. There won't be much suspense about who will lead Sento to Taka, but I'm working on my teasing. I hope you liked the chapter.**

 **Next Time : One of Fairy Tail's strongest is back. The most powerful team and the threat of the curse.**


	7. Chapter 7 : Titania and Eisenwald

**OK guys, here is the new chapter. I hope you'll like it.**

 **Before starting, I'll have to put some light on things some of you pointed out.**

 **First : concerning the Fullbottles. Actually, only the Touto ones are going to be in the story. But I intend to cut the story in segments. The first one from the beginning to Tenrou, the second one from Tenrou to Tartaros and the last one from Tartaros to the end. Those segment are different stories : basically, it's going to be a trilogy. So since there is 3 states in KR Build (Touto, Hokuto and Seito) the bottles will appear in one part each. So for the moment, it's going to be just the Touto ones.**

 **Second : concerning how Sento will get the FB. I already have planned how and when he is going to find the bottles. For some, I had almost no hesitation. For other, I found ways, but I wasn't so sure. And then I saw FanFictionHunter review asking if Smash will appear and to be honest, I completely forgot about them. So there will be Smash, people from Fiore, known or not, becoming Smash because of Sento's lost bottles. For example, I had to make some changes in this chapter.**

 **Also someone asked if I was thinking about shipping Sento with someone. The answer is no, or at least for the moment. Maybe if I found the ideas, but if not, he won't be paired.**

 **And one more thing. Thanks to your reviews, I have new ideas and so I updated the last chapter, the part were Don explain his 'power' and the teasing at the end, because it wouldn't stick with what I'm changing, mainly about the bottles and their discoveries. Sorry for the inconvenience.**

 **I hope you all have answer to your questions. Here we go !**

 **P.S. : I don't own Kamen Rider Build nor Fairy Tail.**

 **Chapter 7 : Titania and Eisenwald**

 _Italic : Sento's though_

/- Magnolia -/

\- "It sucks."

Sento was currently walking in Magnolia's street, heading to the guild and he was depressed. He had spent the whole night without any sleep, working on his projects.

Firstly, he need to find his remaining devices and Fullbottles. It wasn't that big of a problem, since until now, he found Fullbottle quite easily since they were literally coming to him by themselves.

Secondly was the reason why he was up all night : contacting his world. He discovered that his Build Phone managed to pick up a signal. To Sento, that meant that he could find a way to contact his friend and maybe asked if they could find a way to help him or at least know if they had discover something on their side. But the signal, of course wasn't strong enough for a inter-dimensional communication, but he was sure that this world had something to amplify the signal. But that meant that he'll need to understand how communication worked here, and it was kind of hard.

Could it be worse ? Of course, since he had no idea on where to start. If he wanted to know what to do to amplify the signal, he'll need basic understanding of magic, which meant finding what he still haven't found : how people from this world could harness the power of the bottles ?

 _"Everything seems linked to this question. If I could get that answer, it would be much easier."_

He reached his destination and entered the guild without lifting his head. But something was off : the guild was calm, TOO calm. He learned that this guild had 3 particularities : First, they were all like family. Second, all notion of logic and normality were inexistent with them. And third, the guild hall was never EVER calm. Deducing that something was not normal, he lift his head and saw why. In the middle of the hall was someone he never saw before. It was a girl wearing knee high boots, a skirt and armor on the upper half of her body. She also had blood red hair and beside her was a gigantic horn, probably belonging to a beast just as big.

Sento didn't knew who that girl was, but judging by the way everybody seemed tense and even sweating, she was either feared or really powerful or probably both. Since the tension was seriously heavy, he discreetly slipped to the bar to talk to Mirajane.

\- "Hi Mira. Hum, who's that ?" murmured Sento, looking at the redhead, now seeing the face of a beautiful woman who seems to shine with proudness and power.

\- "That's Erza Scarlet. One of the most powerful mage of Fairy Tail.", answered the barmaid. "She just came back from a mission."

 _"And I'm ready to bet it was to slay some monster."_ Though Sento looking at the horn. He noticed that the master wasn't on the bar.

\- "Where is Makarov ?"

\- "At the guild master's annual meeting, in the city of Clover.", answered Mirajane

\- "I actually have a favor to ask both of you." Sento turned to Erza, who just talked with Natsu and Gray. "I heard something troubling at work. I would usually ask the master about this, but since it's urgent… I need your help. You'll come with me right ?"

This shocked the whole guild. Apparently, Erza asking for help wasn't a common occurrence and it probably meant that it was something really big.

\- "We'll leave tomorrow. Prepare yourself." She said, not even waiting for Natsu and Gray's answer, those two clearly not wanting to work together, Natsu even trying to disguise Lucy as himself just to avoid that.

\- "Erza… Natsu … And Gray. I never thought about it but, " said Mirajane trembling. "It might be the strongest team in Fairy Tail."

 _"I already saw Natsu's power and I'm not sure if I want to see the others two."_

/- Magnolia Station -/

Sento, Lucy, Gray and Natsu were at the station, waiting for Erza and the two rival were already fighting, much to Lucy's annoyance. She was asked to come by Mirajane to act as a mediator between those two. As for Sento …

/-Flashback-/

\- "You should go too, Sento. I'm sure Erza will be really interested in seeing your kind of power."

\- "Sorry, Mirajane. But I'd prefer staying here this time, I have a lot of calculation waiting for me."

\- "Please. It would make me happy." She said with a smile.

Sento was about to say no again, but when he looked at her, he felt as if he was in front of a beast, ready to pounce on him if he made one wrong move. Kind of like with Misora when he and Ryuga were to noisy, preventing her from sleeping.

/-Flashback end-/

And here he was, because he wanted to avoid a monster, just to end up in a team which, according to rumors, was probably MADE of monsters. He was also wondering what kind of weird habit Erza could have. He had become certain that everyone in the guild was weird in a way. And seeing Erza approaching them, he already found a proof of that. She was literally a TON of luggage, clearly packing far too much. But he won't be the one to tell her that.

\- "Sorry… Did I make you wait ?", she asked pulling those luggage like it was nothing.

No one answered, but she turned to Lucy, who introduced herself.

\- "I see. I heard you defeated a mercenary gorilla… You're very promising."

 _"She may have potential as a fighter, but it wasn't her who did those thing. And also, you mixed the fact."_

The red head turned to Sento.

\- "And you are ?"

\- "Oh. I'm Sento Kiryu. Nice to meet you."

\- "I hope you'll be up for the job."

\- "I'll do my best. But what is the job, in fact ?"

\- "I'll answer in to that question in the train."

\- "I don't know what our task is this time but I'll go with you, under one condition." Suddenly asked Natsu.

-"Condition ?" repeated Erza, "Say it."

\- "When we return, fight with me. I'm different from back then." He said, completely serious.

\- "You've really grown up." Said Erza with a smile. "I'm not very confident in myself… but okay I accept."

I have never saw Erza fight, but judging by Gray reaction, it looked like the Salamander had signed his death sentence.

\- "Yosh ! I'M IN ! LET'S DO THIS !" he said, literally on fire.

/- Later -/

Natsu's energy leaved his body as soon as he got on the train. Once inside, after knocking out Natsu just to prevent him form feeling sick and learning that Gray's Magic was Ice Make Magic, allowing him to form anything he wanted with ice, Erza told us about our target. Apparently, while she was on her previous job, she stopped in a bar where she heard some guys talking. They had mentioned 3 words that had caught her attention : Erigor, Lullaby and sealed. Apparently one of those guy was about to unsealed that Lullaby thing for his boss named Erigor.

 _"Whatever that Lullaby his, if it was sealed, then it means it must be dangerous. Moreover, Lullaby ? Like the one parents use to make their child sleep ? Is it some kind of sleeping magic ?"_

\- "I don't get it." Said Gray. "You came across some folks who wanted to break a seal of an unknown magic… Maybe it was just their job."

\- "That's what I thought too, until I remember the name Erigor." Replied Erza

According to Erza, that Erigor is the ace of Eisenwald, a mage guild. He was nicknamed Shinigami because I kept on taking assassination request despite the council interdiction. As a result, their master was arrested and the guild had been disbanded. Or at least it should have.

\- "Eisenwald, despite being ordered to disband, refuse and kept functioning, thus becoming a 'Dark guild'", concluded Erza.

\- "So a dark guild got a hold of this 'Lullaby' and are plotting something.", resumed Sento. "So what is the plan, then ?"

\- "We'll march into Eisenwald."

 _"It's seems like running in head first is something everybody does in that guild. I'm sure Natsu is already ready to go. Wait a minute…"_

\- "Natsu's not here !" noticed Lucy, with some worries clear in her voice.

\- "He probably is still in the train." Said Sento.

Running back to the station, Erza tried to convince the controller to stop the train. When he refused (for obvious reason), Erza asked Happy to do it. And so the cat pulled the emergency stop signal, stopping the train. They then took a magical four wheeled vehicle with Erza driving to catch up with the train and get Natsu back.

/- Later -/

The Fairies and the Rider were all in the magic vehicle with Erza at the controls and they were rushing to the train to get Natsu back. When they were about to reach it, they saw Natsu jumping out of the moving train through a window. He banged his head against Gray, who was on the roof, the two of them falling to the ground. Erza stopped and they all rushed to their comrades.

\- "Happy ! Erza ! Lucy ! You're terrible !" said an angry Natsu. " How could you leave me behind !?"

\- "I'm sorry." Answered Lucy with an awkward smile.

\- "I apologize. I'm happy that you're safe." Said Erza, bringing Natsu's head to her chest in a kind of motherly way, which would have been quite cute he she wasn't wearing her armor, smacking Natsu's head in the process.

\- "How am I safe ? A weirdo tried to pick a fight with me ! " He said. "What was his name, already ? Ei…sen…wald ?"

Hearing Natsu's sentence and remembering what Erza said, the group was shocked that Natsu found himself facing one of those they were pursuing.

\- "IDIOT !" said Erza, slapping Natsu so hard he was sent almost 50 meters away. "Eisenwald is what we are after !"

\- "That was the first time I heard that…" Said Natsu while getting up.

\- "Why weren't you listening to my story !?" asked Erza.

 _"Because you knocked him unconscious in the train."_ Though Sento, pulling out a notebook and taking some notes. _"So, for Erza : prepare way too much luggage and some sort of short term memory."_

\- "He was in the train earlier right ? Let's chase it." Said Erza, strapping herself to the vehicle. "What did he look like ?"

\- "Nothing special." Answered Natsu. "He carried a flute with a three-eyed skull on one end."

Sento frowned at that. As a Kamen Rider, he learned that things like skull and multiple eyes were often a sign of trouble. But Lucy seemed more troubled than he was. After a few second, as if to remember something, she said something that shocked them to their very core.

\- "That flute is the Lullaby, the magic of 'death' ! " she said. "I've only read about it in a book, but among forbidden magic, there is such a thing as 'murder by curse', right ?" she asked Erza.

\- "Yeah… Just like the name, it'll curse the target and cast 'Death'. It's a black magic." Confirmed the armor wearing mage.

\- "Lullaby is worse than that." Continued Lucy. "Lullaby cast the curse of 'Death' on everyone who hears its melody."

Soon enough, everybody was aboard the magic vehicle and rushed after the train because whatever Erigor was after, it couldn't be good.

/- Later, Oshibana Station -/

As the group reached the station, they got down, Lucy having to wear an unconscious Natsu on her back. There was already a big crowd just outside the station, trying to understand what was happening.

The group, led by Erza, approached one of the controller.

\- "What's going on inside ?" asked Erza

\- "W-Who are you !?" answered the controller. Erza then headbutted the guy, knocking him out without letting him answer and got to the next one.

\- "What's going on inside ?" asked Erza to the new controller

\- "W-Wha …" *GON* headbutted.

Erza then did the same things again and again. Lucy and Sento looked at her sweating bullets.

\- "She only likes people who answer immediately, doesn't she ?" asked Lucy.

\- "You know her better know", said Gray, feeling as tensed as Lucy and Sento.

"Almost no patience when asking question. Got it." Nervously note Sento.

Once Erza finished, they rushed inside, straight to the platform where they met with all of Eisenwald, Erigor seating on the train. Lucy put Natsu on the ground, trying her best to wake him up.

\- "I knew you'd come, Fairy Tail." Said Erigor. "We've been waiting for you."

\- "What do you intend to do ?", asked Erza, her magic power swelling up. "Depending on your answer, I might have to make you pay for it."

\- "We just want to fool around." Said Erigor. "We've got no job and we're really bored." He then began to fly, or more precisely float around the station, revealing that he used some kind of wind magic. He then asked a question.

\- "What do they have in a train station ?"

No one answered and after some time, Erigor answered in their place.

\- "Time's up." He said, while knocking on the answer : the station speakers.

\- "You are going to broadcast the Lullaby ?!" Shouted Erza. The news and the implication of what it could mean shocked everyone. With all the people gathered just outside the station, it would be like a genocide. But for Sento, something was off.

 _"I'm ready to bet that the one who will play the Lullaby is going to be protected from it, but then it meant that all the other will die. Unless they have a way to protect themselves from it, but I have a feeling it's not the case."_

Meanwhile, Erigor was explaining why he was doing it : he wanted to wipe out those who lived their lives with their right and ignored those who lost them.

 _"If they wanted to kill people just for that, why this station in particular ? Erigor probably have another objective but what ?"_

\- "You rights will never be returned if you do that !" explained Lucy

\- "Now that we've come this far, it's not the 'right' that we seek, but 'authority'." He said. " If we have 'authority', we can simply wipe off the past and control the future."

At that, one of Erigor main men start using his magic.

\- "What a pity, for you little flies." He said, his shadow dashing to Lucy forming a clawed hand. "To die without getting a glimpse of the Dark Age."

\- "Kyaaah !"

\- "I knew it was you !"

Natsu got up in an instant _("Was it because of that guy voice, or Lucy's shout ?"),_ destroying the shadow with one swing of his arm just in time.

\- "He's revived !" said Lucy with a big smile, happy to see him up just in time to save her.

\- "This time we're on a real battleground !" said Natsu, ready to fight.

Now, everybody was ready for the fight, Eisenwald on one side and the Fairies on the other. As for Erigor, he seemed to have something else planned.

\- "I'll leave the rest to you while I go play the flute." Erigor said to his men. "Let these clueless flies… Feel the power of Eisenwald's darkness.". With that, he flew through the windows, seemingly running away. Seeing him leave, Erza turned to Natsu and Gray.

\- "Natsu ! Gray ! Both of you go after him." She asked. "If you work together, there's no way you would lose to Erigor. Lucy, Sento and I will take care of those guys. No matter what, we have to stop Erigor and prevent him from using Lullaby."

Apparently, Natsu and Gray were busy glaring at each other. But when Erza turned around to look at them…

\- "Are you listening to me ?!"

\- "O-of course !", they answered, playing good friends before going to catch Erigor. But Eisenwald moved next, two of them, the shadow user and some kind of thread magic user, going after Natsu and Gray. Now that fight was unavoidable, Erza pulled out a sword out of nowhere, Eisenwald rushing at them with the same kind of weapon.

 _"Magic sword ?_ _It seems a little light for one of Fairy Tail's strongest mage. I'm sure she have a lot of aces up her sleeves. "_

She sprint to the guys, slashing with speed and precision, jumping, dodging so easily it seems like she was dancing on the battlefield. When some guy tried to shot her with magic, her sword disappeared, being replaced by a spear and in the next seconds, she switched to twin sword, then to an axe.

\- "It's ex-quip." Explained Happy. "She have weapons stocked in a different space and using magic, she can switch between those weapons. But it's just a small part of her power." He ended with a grin.

Indeed, seeing that there was a lot of guys left, her armor seemed to come off and, in a flash of light, she reappeared, wearing a totally different armor with some kind of big skirt, wings and many sword floating around her.

"Usually, mages only ex-quip their weapons. But Erza can ex-quip magic armor to increase her ability. That's her magic : the Knight !"

Then, her sword, as if listening to her words, started to move.

 _ **CIRCLE SWORD !**_

Her swords whirled around, slashing a lot of men in one attack. That's when she pulled out of the fight one of Erigor general that they recognized her : Erza the Titania !

 _"Wow, many kind of armor, each with his own power. It's a lot like a Kamen Rider. No wonder she is so strong."_

The last general of Einsenwald, named Karakka, then flee the scene, fearing for his life. Following Erza's suggestion, they were ready to go after him when something happened.

*CRAAAAAAAC*

The roof exploded, chunk of stone falling in a big cloud of smoke. They could see a silhouette inside.

\- "What's that ? Eisenwald had reinforcements ?", asked Erza, looking at the dust.

When the smoke cleared, they could see clearly what was inside and it shocked Sento. It wasn't a human, but some kind of monster. It had a huge beak on his face, no visible eyes, big orange wings, blood red talon like claws, and his body was covered in feather looking scales.

\- "What the hell is that thing ?" asked Lucy, shivering at the sight of the beast.

\- "It's a Smash." Said quietly Sento, not believing his eyes.

\- "A what ?" asked Happy, not understanding.

\- "A Smash. In my world, they are humans who got corrupted by something called Nebula Gas. They then become monster, losing all sense of humanity. That's what a Smash is."

 _"But where does that one come from ? Wait a second…"_ he took a good look at the Smash. _"No, could it be …"_

\- "Wait ? What do you mean another world." Asked Erza, now back in her normal attire, looking at Sento.

\- "Oh yeah you don't know. Sento is from another world." Explained Happy. "He came here to found his enemies."

\- "Later for the explanation. Let me take care of this thing." He said, pulling out two bottles.

 _ **RABBIT ! GATLING !**_ _ **ARE YOU READY ?**_ "Henshin !"

When the Snap Ride Builder appeared, Erza took a step back in shock. When Sento was transformed, he was wearing the classic red rabbit part, but also a new grey one. His eye was shape like a gun barrel and his mechanical looking arm had a shoulder pad looking like an ammunition belt.

 _"An armor magic ? Or is it really magic since he seems to be from another world ? Anyway, lets see how good he is."_ Though Erza, intrigued by Sento's armor.

Out of nowhere, Sento pulled out a black and orange gun. He took it and proceed to shot at the bird monster. When the monster took off and started attacking from the air, sending bird shaped energy bullets at the Rider. Sento dodge the birds and, using jumped high, higher than the monster. Still in the air, he took out the Rabbit Fullbottle from his driver and took another one.

 _ **GORILLA ! GATLING !**_ _ **ARE YOU READY ?**_ "Build Up !"

Now wearing the big armed brown armor, he punched the monster, sending it back on the ground. Landing and seeing the Smash struggling to get up, he decided that it was time to finish it.

\- "The laws of victory are set !"

 _ **RABBIT ! TANK !**_ _ **BEST MATCH ! ARE YOU READY**_ ? "Build Up !" _**HAGANE NO MOONSAULT ! RABBITTANK ! YEAHHH !**_

Now wearing his standard armor, he took his Drill Crusher out, plugged the Gorilla bottle inside.

 _ **READY, GO ! VORTEX BREAK !**_

The Spiral Blade then began spinning at a high speed, cloaking itself in a brown energy. Then, Sento swung it at the monster, sending a fist shaped energy blast who knocked out the Smash. Sento, unmorphing, goes to the Smash and saw it disappear. In his place was a middle aged man, next to a small orange bottle : the Taka Fullbottle.

\- "Ugh… My head. What happened ?" asked the man, waking up.

\- "We should be the one asking that question. What happened to you ?" asked Sento, kind of impatient to know how that guy changed into a Smash.

\- "Well, I'm a hunter. I was hunting deer when I saw that strange bottle. I picked it up when I saw a bear just behind me. I shouted out of fear for my life and next thing I know, I wake up here."

As Lucy and Erza were trying to have more information, Sento's brain was working at one thousand percent of its capacity.

 _"That guy was changed became a smash because of the Taka Fullbottles ? But why ? It can't be just because of the bottles power. If that was the reason, then Lucy should have became one since she already used Harinezumi's power 2 times. Then why ?"_

/- Later -/

The team was now facing one seemingly impassable obstacle : a huge wall of wind surrounding the station, left by Erigor. When Gray and Natsu came back, they learned that Erigor's real target was the guild master in Clover and that this wall was there to prevent them from intervening. They tried to find the only guy who could nullify the wall of wind, Eisenwald's Kageyama, but he was stabbed by his own guildmates, so now the Fairies were stuck. Natsu was trying to force his way through the wall when someone found the solution and it was Happy.

\- "Aaaaaaahhh !" shouted The cat, surprising us. "Lucy I just remember." He said before taking something out of his bag. It was a golden key, with Virgo's symbol.

\- "That's … Virgo's key ?!" said Lucy not believing her eyes. She then regain her seriousness. "I love the offer but it is not the time. We have to find a way to get out of here."

A tuft of hair suddenly stood up on Sento's head as he remembered about Virgo.

\- "That's precisely why we need that key Lucy. Happy his right." Said the scientist. "If I remember correctly, Virgo's power allow her to move freely under the ground. We could use her to escape."

Realization dawned on everyone's face as they understood what that mean. Without losing an instant, Lucy took the key and summoned Virgo.

 _ **OPEN THE DOOR TO THE VIRGIN ! VIRGO !**_

The maid came out, shocking most of them since it was not the gorilla maid from the last time, but a small and pretty young girl. She explained that since she is loyal to her master, she took any appearance her master want. When the formalities were done, she dug a tunnel allowing the group to exit the station. Once on the other side, they quickly realized that Natsu and Happy weren't there.

\- "Happy is probably taking Natsu to Erigor right now. I'll try to catch up with them." Said Sento. He then took out his Lion Fullbottle and plugged it in his Build Phone.

 _ **BUILD CHANGE !**_

He threw his phone who then became his bike, the Rider Machine. He pulled his helmet on and heard Erza talking to him.

\- "We will join you as soon as possible. Go and help them."

\- "No problem. Leave it to me." He said before speeding out.

 **Ok, it's done. I'm sorry if it looked like I rushed some moment, but I was starting to feel like this chapter was getting too long so sorry. Anyway, I hope you will like it.**

 **Next Time : A Shinigami and a flute ? Bad news ! The common factor and a device ? Good news ! Take off, Build !**


	8. Chapter 8 - Erigor, Lullaby, Discoveries

**Ok guys, here comes the next chapter. But before, let's answer some reviews.**

 _ **Kamen Rider D-Cide**_ **: Yeah, I'm going to use the Dragon Lock Best match. As for a fight versus Natsu in that form, I still don't know.**

 **Someone asked me if I could give a clue about when Ryuga will appear, so here it is : Ryuga will appear in an arc where another dragon appears.**

 **So now, let's get down to business !**

 **I don't own Fairy Tail and Kamen Rider Build.**

 **Chapter 8 : Shinigami, Lullaby, common factor and device.**

\- "How can that cat be so fast?"

Sento was actually on his Machine Builder, following the railroad trying to reach Natsu and Happy, who took off at the moment they were freed from Erigor's prison at Oshibana Station. Sento drove as fast as possible with his motorcycle but he couldn't catch up with them. In fact, the gap between them was growing.

 _"Natsu can't handle a train, but he have no problem flying at that speed ? I know there are people who feel motion sickness depending on the vehicle, but that is just ridiculous. That guy is just incomprehensible."_

When he saw a stream of fire aimed at the sky, he knew he wasn't that far. After some time, he finally saw them on a bridge. He could see Natsu facing Erigor with Happy watching from the side. He could see that Natsu was in a pinch : he was covered in bruise and facing Erigor, who was covered in what looked like some kind of armor made of wind. Each time Natsu tried to used his flame, they disappeared as soon as he was close to the Shinigami, as if they were blown out.

 _"I see. By coating himself in wind, he blow out the fire on Natsu before it could reach him. He may be a criminal, but he is smart."_

Just then, Erigor used a spell sending whirling destructive wind at Natsu, destroying the bridge. When the smoke cleared, Natsu was out cold. Sento couldn't let Erigor reach Clover and the guild masters, so he pulled out the Drill Crusher and, reaching the wind clad mage, slashed him. It didn't do much damage but it gave him the time to stood between Erigor and Natsu.

\- "Sento !" shouted the blue cat happy to saw the Rider.

\- "So you are here to, uh ?" Said Erigor, before grinning. "If that is all you can do, "he said, pointing to the Drill, "You won't be that much off an opponent."

\- "Please, I'm much more than your opponent. I'm your bane." Said Sento, his ego controlling his reply.

In the took his Driver out, putting it on and pulling out two bottle.

 _"Let's see how strong his that armor."_

 _ **LION ! GATLING ! ARE YOU READY ?**_ "Henshin !"

The Snap Ride Builder then close on him, encasing him in a marigold and gray armor. On the ground, Natsu look up. He saw Sento in a whole new combo. It was also the first time he saw the Lion Fullbottle used that way. The marigold part had an eye shaped like a lion with his mane going out while his right arm had a lion head shaped gauntlet with some sort of tail pointing out of the shoulder. Erigor was wide eyed at the transformation, not believing what he just saw.

 _"What the hell was that ? Is it some kind of ex-quip magic ? Tch, he won't stop me no matter what." Though the Shinigami._

Sento rushed at Erigor, throwing a punch with his right hand, building up some golden energy in his fist. He made contact and hit Erigor, but the punch had lost some power due to the storm mail. It still shocked Erigor, who took the blow without moving but the fact that his punch had enough power to break through, even partially, surprised him.

For Sento, it was also a shock. He knew that this storm mail was powerful, but he didn't though it could weaken his power that much. He was sent back when Erigor sent wind blades at him, and Sento countered with his Hawk Gatlinger, shooting at Erigor, but the bullet couldn't reach their target because of the wind.

\- "I already lost to much time." Erigor said. "It's time to crush you once and for all."

 _ **STORM BRINGER !**_

The swirling blast of wind was coming straight for Sento. He knew that this would be too much for him but since Natsu was still behind, he had to be a shield for him. He turned the lever of his Driver to counter Erigor, hoping it would be enough.

 _ **READY, GO ! VORTEX ATTACK !**_

Sento punched at Erigor, sending a big yellow energy blasted shaped like a lion head. Alas, the attack wasn't strong enough to stop the opponent blast and Sento was sent onto his back.

\- "Don't worry. I'll send the geezers over to your place soon enough." Said Erigor, turning his back to the boys. "With the Lullaby's melody, of course."

 _"Shit, I have to stop that guy, Natsu is not in shape. I almost forgot that I have one last ace in my sleeve."_ He though, pulling out his Taka Fullbottle when…

-"The Lullaby…What ?"

To everyone shock, Natsu was getting up despite his wound and shout to Erigor.

\- "If you want grandpa's head, fight us fair and square ! ", he said, igniting his hand "If you're not courageous enough to fight, don't even bother !"

He rushed to punch Erigor but his flame was blown out and he was sent back.

\- "BASTAAAAAAAARD !"

Natsu was in flame, venting his frustration on the railroad.

\- "Why can't i get close to you !? I don't get iiiiit !" he shouted, his fire growing in intensity.

\- "It's such a bizarre magic." Said Erigor, speaking of Natsu. "His emotions seem to be manifested directly into the flame."

A tuft of hair stood up and Sento look up to Erigor, wide eyed.

 _"What did you just said ? His emotions … ?"_ Sento then saw the Lion Fullbottle, just beside Natsu. It was shining and the more Natsu was angry, the more it was shining. _"Wait, it the bottle…reacting to Natsu ? But then …"_

\- "GRAAAAAAAAAAAAAAAAAAAAAAAH", Natsu roared, holding two half of a melted rail in his hand, the heat around him skyrocketing.

At that moment, Erigor, Sento and Happy took note of something. The storm mail was being sucked by the flame. Sento understood why immediately.

"Natsu's fire is heating up the air to the point where It create an ascending current and low pressure. This difference in pression is sucking out the air around him ! He his literally sucking the storm mail off Erigor !"

But it wasn't enough, until Happy said something.

\- "Natsu !" he shouted, grabbing Natsu's attention. "You can't win, Natsu. Let's leave it to Gray."

\- "WHAAAAAAAAAAAAAAAAAAAAAAAT ?"

Natsu, not liking what he just heard, was even angrier now, his flame power growing up with his rage. Sento decided that he could try to 'help', and also trying to confirmed something.

\- "He's right. In fact, I think Gray is a much better hero than you. Probably the kind of hero Lucy like."

Hearing that last part was the last straw for Natsu, whose power was now enough to melt the rail all over the bridge. Unfortunately for Erigor, all this rage was headed straight at him.

\- "I'LL TAKE YOU DOWN !" he said, covered in flame and launching himself headfirst at Erigor

 _ **KARYU NO KENKAKU !**_

He crashed in Erigor like a missile, sending the Shinigami high in the air, before he land on the ground, knocked out.

 _As Natsu was talking to Happy, about what the cat has said, Sento was thinking about what Erigor said about emotion. "Could it be that ? It must be. So in this world, the emotions is what the people can use to harness the Fullbottle power. Then why aren't the user changing into Smash like that guy at Oshibana ? Wait. That guy wasn't a mage. The you need to be a mage, or at least have a minimum of control on your magic, to be protected. Then, does it mean that someone with enough control on his emotions and magic could harness more power from the bottles ? I have to test this theory."_

\- "And you ! " Natsu suddenly addressing to Sento. "Why did you said those things !"

\- "What is bothering you ? The fact that Gray's a hero or the fact that Lucy might like him ?" Sento asked, toying with him a little.

\- "What are you talking about ? How can Lucy like that exhibitionist ?"

\- "So you're jealous. Interesting."

\- "I-I'm not jealous !" he said, his cheeks suddenly burning. _"Why I'm even embarrassed ? It's not like he said the truth. Right ?"_ Natsu asked himself, not even sure about the answer.

A few moment later, Lucy, Erza and Gray arrived. After all the thanks, they were ready to go, when Kageyama, still in the vehicle, drove away straight to Clover, picking up the Lullaby.

\- "That bastard ! How could he ?! We even saved him." Shouted Lucy

\- "We're are going after him" Sento said, calling his bike.

/- Later -/

When the team reached Clover, they rushed to where the meeting was held. Once there, they saw Makarof, standing in front of Kageyama, ready to play the Lullaby. But when they tried to stop him, they were stopped by Blue Pegasus's master, Bob, and Quatro Cerberus's master, Goldmine. Kageyama seemed to be struggling, like he was hesitating.

\- "Nothing will change." Makarov suddenly said. And judging by Kageyama's reaction, he seemed to know what the shadow mage was thinking. "Weaklings will stay weak forever. But weakness is not evil, since human beings are weak creatures to begin with. Alone, you feel nothing but insecurity; that's why we form guild. That's why we have nakama. We walk together in order to live a strong life. The clumsy ones will run into more walls than the others. And it may also take them longer to get there. If you believe in tomorrow and put yourself out there, you can naturally obtain your strength. That's how you'll be able to smile and live strong, without having to depend on such a flute, of course." He ended with a grin.

With that, Kageyama dropped the Lullaby and fell to his knees, admitting his loss. The group then rushed to Makarov, congratulating him for what he just did.

 _"He took away his desire to fight just by talking to him. That's one great man."_

But as everyone was feeling happy that this chapter was close, someone decided that it need one last twist.

\- "Congratulations, mages." Said a growling voice. Turning to the source, the group was now facing a platoon of Shocker soldier, led by a monster who seemed to be a mix of a stag beetle and an eagle. He had wings, some kind of shell on his body, with feather on the upper half. His feet were talons, he had 6 arms, 2 strong human like arms with claws, the 4 others were more like small insect legs. On his face was composed of a big beak, surrounded by 2 big mandibles and 6 blood red eyes, 3 on each side of his face.

\- "My name is Staggle and I'm here to take that flute back to our boss." He said, gesturing toward the flute still on the ground. "After all, a flute who kill anyone who hear its melody, it would be nice to use it in our world."

\- "Sorry. But that flute is not going anywhere." Said Sento, taking a step toward the monster.

\- "Ah, here you are. Kamen Rider Build. Sorry, but we weren't asking for your permissions." Ha said, before turning to his men. "Guys, let's go take that flute !"

With a war cry, they rushed forward. Sento then took two of his bottles.

 _ **RABBIT ! TANK ! BEST MATCH ! ARE YOU READY ?**_ "Henshin !" _**HAGANE NO MOONSAULT ! RABBITTANK ! YEAHHH !**_

Sento morphed, in front of surprised guild master.

\- "What kind of magic is that ?" asked Goldmine, still shocked by what he just saw.

\- "It's a long story, I'll explain later." Answered Makarov

Sento had no trouble dealing with those soldier but he was too busy to notice Staggle taking off and diving to pick up the Lullaby. Alas, no one was fast enough to stop him.

\- "Ha ! That was to easy, now I'll bring this little thing to the boss. Bye, losers !"

Sento, seeing the flying monster fleeing the scene remembered that he had a way to catch that guy.

\- "Shit ! He is getting away !" shouted Gray.

\- "Don't worry. I've got it." Reassured Sento.

\- "You know Sento. From what I know, you didn't have wings."

\- "Not until Oshibana, at least." Finished the scientist, pulling out an orange Fullbottle.

\- "Hey ! Isn't that the bottle that poor old man had when he was a monster.", remembered Lucy

\- "It is. And now watch that."

Taking his Rabbit and Tank Fullbottles, he then shook a gray one and orange one.

 _ **TAKA ! GATLING ! BEST MATCH ! ARE YOU READY ?**_

Turning his lever, two liquid, one gray and the other orange, came out of the driver via pipes and filled two half of armor on the Snap Ride Builder.

"Build Up !"

The two closed on him, changing his armor.

 _ **TENKUU NO ABARENBOU ! HAWKGATLING ! YEAHHH !**_

Sento Gatling half was now completed with the orange taka half. The eye was shaped like a bird head with wings spread out and if his right arm was quite normal, he now had small wings on his back. Those wings then unfolds, allowing Sento to fly to the monster. He caught up with Staggle and kicked him to stop him. He then took out his Hawk Gatlinger and began shooting at the monster. He flew around the bird monster, making bullets rain on him all the while dodging the bird attack. After some time, he finally decided to finish it. He began spinning the Revol-Magazine, building up the power as well as the bullets.

 _ **10 ! 20 ! 30 ! 40 ! 50 ! 60 ! 70 ! 80 ! 90 ! 100 ! FULL BULLET !**_

As Sento was spinning the Revol-Magazine, a white energy spherical graph appeared around the monster, trapping him inside with Sento. Sento then turned his Driver lever, ready to finish it.

 _ **READY, GO ! VORTEX FINISH !**_

Sento then unleashed 100 bird shaped bullets at the monster, the quantity and power resulting in a series of green explosion filling the graph.

\- "It's not finished yet, Kamen Rider ! This Lullaby is not the only thing that man left in this world ! Soon enough, you and all your friend will be all annihilated !" After that, Staggle exploded, lighting up the night skies.

When Sento landed, the Lullaby rolled on the ground, dropped by the now destroyed monster. People were starting to come, his friend to congratulate him and the other master to know what kind of magic he had, which was kind of creepy having all those all guy sticking to him like mussels on a rock. But they were stopped when they heard a creepy voice.

\- "Ka..Ka..Ka.. You mages have no guts." They all looked down and saw to their stupor that the voice came from the flute, and a dark mist was seeping out of it.

\- '"It can't hold it any longer. I'll just eat you all myself."

The mist was growing in size and a few seconds later, it formed a gigantic monster made of some kind of wood. Apparently, Lullaby was not just a flute, it was a monster.

\- "Let me consume your pitiful souls…"

\- "Oh my… This is bad." Said bob, his worries clear despite his ever smiling face.

\- "It's the devil from the book of Zeref !" said Goldmine, grabbing a now unmorphed Sento's attention.

 _"Zeref ? Who is that ? And how can that thing came out of a book ? That Staggle said that Lullaby wasn't the only thing that 'That man' left behind. Was he talking about that Zeref ? If that's the case and that guy made other things of the same kind, I can't let Shocker put their hand on them."_

\- "I'm starving to death. So I'm going to eat your souls." Said Lullaby

\- "What !?" shouted Natsu. "Souls are edible ?!" he asked Gray

\- "How should I know ?" shouted the ice mage.

\- "That devil is the Lullaby itself. Meaning it's a living magic. That's Zeref Magic."

\- "Dark Mage Zeref. The most atrocious mage in the history of magic."

 _"Seems like Zeref is the ultimate dark mage. Also, living magic ? That guy could give life to magic ? From a scientific point of view, that guy is probably a genius. Well, not as much as me, but a genius nonetheless."_

When Lullaby open his mouth, ready to eat the souls of all those around him, everybody took got scared. Everybody but 3 people, Natsu, Erza and Gray, who rushed at Lullaby. Erza ex-quip into the same armor she used at Oshibana and slashed at Lullaby's leg, stopping him. Meanwhile, Natsu was climbing on the monster, before kicking it in the face. Turning his head to Natsu, it unleashed several magic sphere. The dragon slayer dodge them but they were now headed to the Guild Masters, but Gray stood in between.

 _ **ICE MAKE SHIELD !**_

\- "An ice alchemy mage ? He won't make it in time ! We'll get it !"

But the masters were wrong, since a wall made of ice appeared in the blink of an eye, stopping all the shots. Gray then took another stance, this time to attack.

 _ **ICE MAKE LANCE !**_

Many arrow-like spears made of ice were shot straight at Lullaby, literally destroying a part of his belly. It was now time for Erza and Natsu to strike. The redhead ex-quiping into a black armor named "Black wing Armor", boosting her offensive power and Natsu ignite his two hands before joining them.

 _ **KARYU NO KOEN !**_

The fire attack created a huge explosion when it hit Lullaby's head while Erza's attack literally cut open the monster. Unable to withstand so much destructive power, he fell on the ground. Lullaby was now history.

\- "Wow, they are really powerful. It really is Fairy Tail strongest team." Said Lucy, whose eyes were glued to Natsu.

\- "Looking at something good, Lucy ?" asked Sento with a knowing smile.

\- "W-What ? N-Not a-at all, what are you talking about ?" she asked, trying to hide her red face.

Sento smile at this before hearing a beeping noise, coming from where he had fought with Shocker. Here, on the ground, he found come kind of walkie-talkie with a big screen. He saw on the screen a notification about an missed call. He opened it and heard someone.

\- "Ok, here is the home team. We are working on the creation of a new portal to send you back up. Pass the message to the other. Home, over."

When the message ended, Sento's hair lift up. This device could communicate with his home world ! If he could work on it to make it work with his Build Phone, he might be able to call his friend. Smiling, Sento put the device in his pocket before going back to the others.

Makarov was smiling like an idiot, really happy with the fact that the other guild master said that they had a debt to them. But when they turned, those smiles disappeared. Lullaby had fallen on the meeting site, which was now just a pile of ruin.

Now chased by angry guild masters, the Fairies and the Rider were running back home, putting a definitive end on this story.

 **Ok, that's it. A little short but I had a little less motivation on it, but I'll pull myself back up. The next chapter will be more of an exclusive, taking place in the normal story, but it will be more like a filler, a transition. I hope you'll like it.**

 **Next Time : a dragon at the council, an explanation, an invisible enemy and a gift from the mist.**


	9. Chapter 9 : Judgement, Theories, S-class

**Hello guys ! I hope you're all well. Here I come with the 9** **th** **chapter.**

 **Also, I would like to say once again that I'm new in the fanfiction world, so I'm still working on some things, like the teasing. So I hope those I made won't lead you to false hope. If that's the case I'm sorry.**

 **And also, I'd like to remember that I'll try to get a new chapter out each week at least, sometime It will be less, sometime it will be more. It will depend on my inspiration and other things.**

 **Anyway, let's go !**

 **Chapter 9 – Judgement, Explanation and Second floor.**

 _Italic : Sento's though_

That morning, a few day after the Lullaby incident, Sento was in his basement, working on his theories about the link between this world magic and the nebula gas. He couldn't deny the fact that he had to use a notion that was clearly not scientific but it's not like he had a choice. Also, he was working on the device he found at Clover, left by some Shocker Soldiers and he had almost finished, meaning he would soon be able to contact his world.

 _"I wonder if they found some solution, or at least if they found where was Shocker other portal."_ He though remembering what the Shocker monster, Staggle, had said back at Clover.

He left his house and head to the guild. He had to ask Makarov if he could use the hall as some kind of conference room to explain what he found; if his calculations were rights, it would mean that his Fairy Tail's friend could help him even more than before. But when he entered the Guild, he clearly didn't expect what he saw.

Everyone was sitting at the tables or at the bar, not saying anything and the air was heavier than lead. Clearly something bad happened.

\- "LET ME OUT ! LET ME OUT OF HERE ! LET ME OUT ! " begged a small voice coming from a jar on the counter. It was a small lizard, asking Mirajane to free him from his glass prison.

\- "Natsu, be quiet." Answered the barmaid with a small voice, her usual cheerfulness gone. "You'll act recklessly if we let you out."

\- "I won't ! " swore the lizard, now Identified as Natsu. "Let me get back to my original form."

\- "Then you'll go and try to rescue Erza won't you ?" asked Mirajane, bringing her face close to the jar.

\- "Wait, what ? Erza is what ?" asked Sento, not understanding what all of that means.

They then explained it to Sento. When Natsu and Erza were fighting just outside the guild, just like Erza promised to Natsu before going after Eisenwald, they were stopped by a messenger from the council, coming to put Erza under arrest, accusing her of damage property and 11 other crimes linked to the Eisenwald incident. To Sento, it seems like something was off. Why would they arrest Erza specifically and not the others ? After all, Lucy, Natsu, Gray and Sento where there too and could be accused of the same thing.

As Lucy stood up, asking to go testify for her friend, the master stopped her.

\- "Have patience." He said "No matter how fast we try to get there, we'd be too late anyway."

\- "Let me out !" Natsu asked again.

\- "Are you sure you want to get out Natsu ?" asked Makarov, and surprisingly, Natsu seemed to hesitate.

After that, Makarov shot at Natsu who, in a puff of smoke turned into Macao. The fire mage confessing he took Natsu place because of the debt he had to the Salamander, probably talking about the Balkan incident. And if Natsu wasn't there, then there is only one place where he could be right now.

\- "He probably is at the council. Do you mind if I try to get him back before he does something stupid ?" asked Sento.

\- "Well, if you want. Go. " said Makarov

\- "Oh. And when I'll come back, I'll need you to gather everyone, I have made some discoveries that I would like to share."

\- "I'll do it. Now go, you are probably already late."

Sento nodded, before taking out his bike and driving to the council.

/- Later, Council of magic -/

When Sento reached the council, it seemed like Natsu already came. One wall was destroyed and Sento heard two guards talking about two Erzas in the court room.

 _"Guess I found out what Natsu tried to get Erza out."_

Taking the Rabbit Fullbottle in his hand, he let its power flowing through him, allowing him to run past the guard without being noticed. Now inside the building, he just strolled, trying to find the councilmen's to asked them to free tell him where his friends were; asking nicely might succeed after all. When he found them, they were in the center of the court room, talking about what just happened.

\- "I can't believe it. Those Fairy Tail's wizards are as reckless as they are dangerous."

\- "I wouldn't say that. I found them rather amusing." Said a blue haired guy with a red tattoo on his right eye and dressed in white.

\- "You can't seriously say that after what they just did, Sieglein !?" said one the elders, gesturing to the hole just behind Sento. That's when the group saw him.

\- "And you ! Who are you and what are you doing here ? And more importantly, where are the guards ?!"

\- "I didn't saw anyone when I was inside the building. I think you should improve security." Said Sento, in a serious tone. "But I'm not here for that, I'm here for Erza Scarlet and Natsu Dragneel."

\- "Another one of those troublemaker, can that day be more annoying." Muttered one of them." Titania and Salamander are in jail and no matter what you say, it won't change our mind."

Just then, a window shattered, sending shards of glass all around the court room. Landing on the ground was a creature with a blue scale covered skin, sharp claws, a long pointed tail and a kind of dragon head. At the sight of this, the councilmen's all gasped.

\- "I-Is that a dragon ?"

\- "Not it is not." Said Sento, drawing the attention of the confused group, minus Sieglein who seemed calm, far too calm. "Or at least, not the kind of dragon you'll find in this world."

\- "What are you talking about ?"

\- "I'll explain after that thing is gone." Said Sento, taking out his Driver and two bottles, surprising the councilmen's.

 _ **GORILLA ! DIAMOND ! BEST MATCH ! ARE YOU READY ?**_

The appearance of the Snap Ride Builder carrying the brown and cyan armor halves shocked the councilmen's, who took a step back, at the exception of Sieglein who just frowned.

\- "Henshin !"

 _ **KAGAYAKI NO DESTROYER ! GORILLAMOND !**_ _ **YEAHHH !**_

Now ready, Sento rushed at the Smash, who blew some kind of blue fire at him, forcing him to jump out of the way, before rushing again. He then punched the monster in the guts, making him go back a few meters, but the Smash managed to stay on his feet.

 _"This is one tough Smash."_ Though Sento as he block the Smash arm with his left one. He punch again to make the smash to throw him back and used the small calm moment to change his bottles.

 _ **TAKA ! GATLING ! BEST MATCH ! ARE YOU READY ?**_ "Build Up !" _**TENKUU NO ABARENBOU ! HAWKGATLING ! YEAHHHH !**_

Taking out his Hawk Gatlinger, he then spun the Revol-Magazine.

 _ **10 ! 20 ! 30 ! 50 ! 60 ! 70 ! 80 ! 90 ! 100 ! FULL BULLET !**_

With one hand, he grabbed the Smash and took off with him, sending him in the sky, while turning his Driver lever with his other hand.

 _ **READY, GO ! VORTEX FINISH !**_

The white energy spherical graph appeared and Sento unleashed the bullets on the Smash. When all the smoke cleared, the monster was still there, but he wasn't going to last long. It was time to finish it.

 _ **RABBIT ! TANK ! BEST MATCH ! ARE YOU READY ?**_ "Build Up !" _**HAGANE NO MOONSAULT ! RABBITTANK ! YEAHHH !**_

Now in his classic red and blue armor, Sento turned his lever to finish it.

 _ **READY, GO ! VORTEX FINISH !**_

Diving into the ground, the white graph appeared, trapping the Smash in the dotted line. Then Sento jumped out and slide along the line, his Tank Roller Shoe heading straight for the Smash. When it made contact, the smash exploded and in his place stood a young man, next to a dark blue bottle.

The Dragon Fullbottle.

\- "What the hell was that ?" shouted one of the councilman before noticing the man on the ground. "Wait. Isn't that the young son of our previous gardener ?".

\- "It is. Why did he turned into a monster ?" said another councilman, before turning to Sento. "I think you own us some explanation."

\- "Of course, but with one condition."

\- "Let me guess." Said another councilman rolling his eyes. "You want your friend back, isn't it ?"

\- "Well, I did save your lives. It's just fair." Sento said, shrugging with a grin.

\- "Well ok. Now talk."

Sento then explain about his origins, his world and the reason why he was there. He had a feeling that if the councilmen's didn't witness the fight with the Smash, it would have been hard to make them believe him.

\- "So about that young man ? He is not really to be blamed right ?"

\- "Yeah, he was just taken over by the bottle power since he isn't a mage. And since you fired his father, he had a reason to came here, for revenge." Explained Sento.

\- "Well, we can't really do much about it. We'll try not to get involved with your mission. I don't think it would be good to meddle with another world business. But we'll try to at least not get in one of those Shocker scheme."

\- "It should be enough. Thanks for listening to me."

Now Sento was escorted to the prison but he was thinking about that Sieglein. There was something odd about him. He was pretty young for a councilman, compared to the other. But it was his reaction. It's like that guy found everything amusing. For Sento, it seemed like that guy meant trouble.

/- Later -/

At the guild, everybody was gathered to hear what Sento had to say.

\- "Ok I'll now explain a little more about my power. See, in my world, my country was one day split into 3 parts by a gigantic wall. These walls diffused a gas called Nebula Gas. A scientific found a way to purify this gas, turning it into a liquid and put it into the Fullbottle. My Driver allow me to use those purified liquid to build my armor halves."

\- "Hum, not that it's not interesting," said Gray." but you said that you had news about a link between our magic and those bottles."

\- "It's true. You see in my world, to use the bottles, you had to have what we call a Hazard Level of at least 3, which is my case." Explained Sento. "But in this world, it's seems there is a link between the power of those bottles and emotions."

\- "Emotions ? What are you talking about ?" Asked Lucy. "You mean like, they react to anger, happiness or thing like these ?"

\- "Lucy, don't tell me you didn't have strong emotions when you used those power."

Lucy though about the two times she used Harinezumi. She clearly was mad at Evaroo and Bora for what they did, she did felt strong anger toward those guys.

\- "There is also magic that play a part in it. When the power of the bottle is used by someone who is not a mage, the power of the bottle take them over because their magic is not cultivated enough to act as a protection. But when a mage use it, his magic power counterbalance the bottle power so he doesn't transform into a Smash."

\- "So, we can use the bottle without any problem ?", asked Natsu

\- "There is still a risk, so I won't let you use the bottle all the time. Just if we need it. But there is one theory i need to test."

\- "Which is … ?", asked Levy

\- "If i'm right, the more control you have on your magic and your emotion, the more power you can use. But I need to test that theory. Gray, can you help me ?" asked Sento, gesturing to the ice mage.

The exhibitionist walked to Sento, who handed him the Gatling Fullbottle. Gray grabbed it and took position in front of a target. He start focusing on a memory to gather emotions or one in particular. Reacting to this, the Gatling Fullbottle let his energy flow to cover Gray's hand, creating some kind of barrel around his hand. When he opened his eyes, his stared at the target and started to gather his magic in his covered hand. He then pointed to the target and unleashed a flurry of ice bullet, shredding the target.

\- "Well, it worked great. You can stop shooting now Gray, you are damaging the guild walls."

Indeed, Gray was so lost in his memory he had shot without stopping for a long moment before stopping.

\- "What did you remembered to feel so much anger ?"

\- "Nothing." He simply replied before handing the bottle back.

\- "Well, anyway. Thanks you for listening." Said Sento, bowing lightly to his audience.

A few hours later, he was with Natsu in front of the quest board, looking for a job; after all, he did had a rent to pay. While he was reviewing the quest, one caught his attention. It was a quest asking to subdue a monster with a image of the said monster. And to Sento, it was more of a Smash than a monster. Even if it wasn't, he wasn't gonna let it pass, since it also paid enough for several rents.

\- "Hey, seems fun. Let's go together with Lucy, she did need money." Said Natsu.

\- "Why not, I don't need that much money after all." With that they head to the bar where Lucy was to tell her they had a job and they head to the station.

/- Later, in the city of Kakureta -/

\- "So, what is the job about exactly ?" asked Lucy.

The group was walking in the street, waiting for the creature to appear. In fact, if he was considered a monster, his appearance was more of a human. Also, he seemed to target woman and more precisely, the participants of a contest taking place in the city. Since that creature was probably a Smash according to Sento, it probably means that the human inside had reason to hate them, maybe a rival.

They met with the man in charge of the contest. The idea was to add Lucy to the competition to be ready to jump into action if the creature came again. When night came, Lucy had to sleep with the other contestant in an hotel while the boys kept guard outside. They were looking out around the building for possible entry point when Sento asked.

\- "What's the problem Natsu ?"

Since the idea of putting Lucy in the competition, he have been weird, and not the kind of weird he usually was.

\- "It just that it would have been easier to find that thing and fight it BEFORE he could do anymore harm." He said, without looking at Sento, as if he tried not to look in the physicist eyes.

\- "Oh, really ? That's all ?" asked Sento, not believing it one second. "It has nothing to do with Lucy, isn't it ?"

Tired of Sento's questions, Natsu snapped back without even realizing it.

\- "Well, if we had done what I wanted, she wouldn't have to be put in danger like that !"

\- "You see, I knew it had to do with Lucy." Remarked Sento with a grin.

Natsu then started processing what he just said, and blushed but before he could countered, he was cut by a cry."

\- "KYAAAAAAAAAAAH !"

Hearing the well-known voice of Lucy, Natsu rushed in immediately, followed by Sento. When they got inside, Lucy was unconscious on the shoulder of a human looking creature, who seemed to be wearing a dark purple outfit with cloth around his head, leaving only his dark eyes visible. He kind of looked like a …

\- "Hey, Ninja guy ! " said Natsu. "Let Lucy down !"

 _"He did look like a ninja. Guess I found the Ninjya Fullbottle."_

The monster dropped Lucy and rushed out by the window, Natsu rushing to check on Lucy while Sento got after the Smash. But once he cornered him, something new for Sento happened : the Smash turned into some kind of shadow. And since it was nighttime, the physicist couldn't see where his opponent was. But then, Natsu came back, and when he seemed to punch the air, he in fact touch the Smash, sending him in a wall. While Natsu was dealing blows after blows, not letting his opponent go, Sento realized that Natsu was using his sense of smell to find the Smash. That meant that Natsu was probably the only one who could beat it, but will his magic be enough, the Smash was born from a power of another world after all. He reached into his pocket and pulled out what was probably the best bottle for Natsu.

\- "Natsu ! Use this !" he then threw the bottle at the fire mage.

Natsu caught it and looked at it. A navy bottle. The Dragon Fullbottle. Without thinking much, Natsu looked where the Smash was, smelling him before harnessing the bottle power. When he hit the monster, his flame were mixed with the bottle power, making his flames go blue. The punch send the Ninja back a good 20 meters, making him lose his invisibility. Harnessing even more power from the bottle, Natsu took a deep breath before using one of his signature move.

 _ **KARYU NO HOKO !**_

The now blue stream of fire headed straight at the ninja, engulfing him before exploding. The detonation was so huge, it could be seen from a good 10 kilometers around. As soon as he was finished Natsu fell to the ground. Apparently using the Dragon Fullbottle wasn't risky just for him. When the smoke cleared, he looked at the Smash to pick up the Ninjya Fullbottle when he saw someone he didn't expect. Jason from Sorcerer Magazine. When he woke up, he explained that he found that bottle a few days ago and when he came here for the contest, his excitation on getting an exclusivity from the contestant triggered the bottle and turning him into a Smash.

 _"That explain the wrecking. In a way, he made sure that if couldn't get an interview, no one else could. But that's probably the worst reason ever. But at least, this quest proved me that the mages can harness a lot of power from the Fullbottles, but also that Dragon is dangerous even for them."_

Now that everything was ok, the fairies received the reward for the jobs and head back to Magnolia.

/- Magnolia, a few days later -/

As usual, the guild was loud and busy. Natsu tried to fight Erza again, since their fight was interrupted by the latter arrest, but it was short lived when Erza took a hammer out of nowhere, smacking Natsu away. Sento was at a table eating when the master suddenly grumbled.

\- "Nothing, just getting sleepy…" he said. "It's him."

Just then, everybody in the guild, with the exception of Makarov, suddenly fell asleep right on the spot. Then, a man wearing a cape, a bandana hiding his face, entered the guild hall and head directly to the request board. He took a request and was ready to go when.

\- "Mistgun." Said Makarov. "Release your sleep magic."

\- "Oh. So you are the famous Mistgun."

At that, Mistgun and Makarov turned to see Sento, still awake and looking at them while eating. The two seems surprised to see him awake, but Makarov soon remember who he was and kind of understood why he seem to be unaffected by Mistgun magic. For the latter, the surprised was bigger.

\- "You don't know him, right ?" asked Makarov. "He is Sento Kiryu. A warrior from another world."

He then explained everything to Mistgun, who took everything with a lot of calm.

\- "I see. Well I wish you luck in finding those Shockers guys. I'll let the guild know if I found anything about them." Said Mistgun, turning to Sento.

\- "Makarov said you fight using small bottles, right ?"

\- Yeah my Fullbottles, why ?" asked Sento. The answer came in the form of a small yellow bottle that Mistgun pulled out his bad.

The Comic Fullbottle.

\- "I found it on my previous job." Explained Mistgun, answering the question before Sento could ask it. Guess you'll use it better than me."

\- "Well thank you." Said Sento before Makarov addressed Mistgun again.

\- "Mistgun, your sleep magic please."

Then Mistgun head to the exit, hile counting down from 5 to 0. When he reached 0, he had already disappeared and everybody in the guild began to wake up. Everybody knew it was Mistgun. When someone explained to Lucy about Mistgun, they said that no one except the Master have seen his face. But someone countered that sentence.

\- "No… I know it as well"

The voice was coming from the second floor of the guild, on the balcony was the owner of the voice, a blonde man with orange eyes and a lightning shaped scar on his face. His name was Luxux Dreyar, one of the strongest member of the guild and judging by the way he talked, it seems like he also is a big douchebag. When Natsu rushed at him to fight, he was brutally stopped by the master's giant hand, slapping him on the ground.

\- "You can't go to the second floor, yet" he said, eyes closed.

\- "Why does that mean, he can't go there yet ? What is so special about it ?" asked Sento after Luxus left.

\- "The request board on the second floor is for S-class job, jobs far more dangerous than the ones on this one." Explained Mirajane, gesturing to the first floor board. "There are currently just 5 mages in the guild who can take those jobs including Luxus, Erza and Mistgun."

 _"I see, so there really is a ranking among the mages. I wonder where I would be if I could fight at full power ?"_

/- Next day -/

\- "Master, one of the request on the second floor is missing !"

That news shocked the guild and what said Luxus shocked tham even more.

\- "Yesterday, I saw a cat with wings stealing one of the jobs." He had said."They just broke a principal rule. When they'll return, they'll get expelled right ?" he continued, now talking to Makarov. "But I doubt that they're coming back. After all, what could they do on a S-class job with their pathetic skills ?"

\- "Luxus, bring them back ! Who else but you can force Natsu to come back !?" asked Makarov, but Luxus didn't gave a shit. Gray on the other side…

\- "Jii-san, that's an unforgivable insult.", Gray said, standing up. "I'll bring them back."

He was leaving when he heard a noise, looking at it, ha saw Sento on his bike.

\- "Need a lift ?"

/- Hargeon -/

\- "Found ya."

Gray and Sento just found Lucy, Natsu and Happy looking for a boat to get to Galuna Island. As the situation seemed to worsen between Natsu and Gray as usual, the two invoked their magic. Seeing this, the guy behind them agreed to bring them to Galuna Island. Natsu used that moment to knock Gray out and put him on the boat. As for Sento…

\- "Well, let's go."

\- "Eh ? You aren't there to stop us." Asked Lucy

\- "Well, you need to know that Luxus is sure that you won't get back from that job with your 'pathetic skills' and I would like to prove him wrong." Explained Sento.

Once on the boat, the old man explained that his name is Bobo and that he once lived on the island but manage to escape.

\- "What kind of curse is it ?" asked Happy

\- "Misfortune will befall you, if you go to that island." Said Bobo. "Can you guys really get rid of this curse?" he asked before revealing his right arm, who look like some kind of monster arm. "This demonic curse."

The team was still trying to understand what Bobo had said when the island came into view. They soon realized something : Bobo had suddenly disappeared and soon, a huge wave tidal wave appeared out of nowhere, before crashing into the boat.

 **OK my first cliffhanger ! Even if I'm sure you all have seen better ones but I'm still new so here's the first try.**

 **Next time : The cursed island, the monster's village, an old demon and memories. Best match under the moon.**


	10. Chapter 10 : Deliora and moon's curse

**So here we are for the 10** **th** **chapter. Hope you'll like it.**

 **I don't own Kamen Rider or Fairy Tail**

 **Chapter 10 : Curse of the Moon and the demon**

 _Italic : Sento's though_

When Sento opened his eyes, he was sprawled out on a beach, surrounded by a rather lush forest. He stood up and looked for the rest of the group, who were not far, gathered around the shipwreck. Natsu was ready to go explore and find a village where the client was supposed to be when Gray stood up.

\- "Wait."

\- "What ? We've already come this far; you can't take us back." Natsu said, and he was right. If Gray wanted to bring the group back to the guild, it was a little late since they already were on the island with no mean to go back.

\- "No. I'm coming with you guys." He answered surprising the group. "It'd irritate me if you guys get to the second floor first. And if you guys get expelled, then that'd be boring." He explained with a smile.

With that, the group enter the forest, looking for the village. After some time, they found it and stood in front of the gate of a huge fence made of wood with a 'KEEP OUT' sign on it. When the group called for someone, two silhouette appeared at the top of the gate.

\- "Who's there ?"

\- "We're mages from Fairy Tail…" explained Lucy. "We saw your request."

\- "Fairy Tail ? We know nothing about you guys accepting our request."

 _"That would be because they took it without having the right to."_

\- "Show me your symbols." One of the man asked

The group did just that, Lucy and Sento raising their hands, Natsu showing his shoulder, Gray lifting his shirt since his mark was on his chest and Happy pushing his bag out of the way, his mark on his back.

\- "They look real. "said the man to his colleague, who in turn asked something strange.

\- "Strip the girl."

\- "Why ? It has nothing to do with this ! " she shouted but it didn't stop from starting to strip her, doing what was asked. "Hey, don't take them off !"

Natsu punched Gray to stop him while shouting : "What the hell you're doing ?"

\- "What ? I'm doing what he asked to enter the village." Said Gray who then looked at Natsu with a questioning look in his eyes. "But, since when did you became like you have a stick up your ass ?"

\- "WHAT DID YOU SAY, STRIPPER !?"

\- "I JUST SAID THAT YOU HAD A PROBLEM, ASH BREATH !"

\- "Uhmm… Sorry i got carried away." Said the guard, his fiend looking at him like 'Really, man ?'

 _"You better be sorry because I have a feeling Natsu could kill you for what you just asked."_

\- "Get in… I'll get the mayor."

Once inside the village, they met the villagers. Every one was wearing a cloak hiding their body. One of them, a kind of sceptre in his hand approached them. It was the mayor, Mocha.

\- "Thank you for coming here, mages." He said. "I'm sorry if this seems sudden, but please look at this. Everyone, took off your robes."

At that, the villagers obeyed and revealed themselves. All the villagers was like Bobo, the man they met at Hargeon. They had a demonic looking part on their body : an arm, a leg or a horn, mainly.

\- "Everyone on this island, even dogs and birds are affected by this curse.".

\- "What makes you think it's a curse ? Can't it be some kind of disease ?"

\- "I've shown this to many doctors, but they all said there is no such disease." Explained the mayor. "Also… The moon seem to have something to do with how we look. Since ancient times, this island has accumulated a lot of moonlight. But suddenly, a few years ago, the moon suddenly turned purple and when it began, our bodies started to change.

\- "Purple ? I've never seen the moon like that." Said Natsu and it was true, evert one in the group agreeing. But then, as the group looked at the sky, they did saw a purple moon, which surprised them. Then, all of a sudden, all the villagers began changing shape. A few seconds later, all the villagers were changed in some kind of demon.

The mayor explained to the group that it was like that each time the purple moon is out and that they change back when morning came back. But apparently, some of them had begun losing their soul turning into real demon.

\- "If we'd let them live, other might get killed by those demons. And even if we'd lock them up, they'd just break out and escape…" he said before taking out a photo. "That's why… I had to kill my son as well. My son, whose soul became evil…"

What shokced the group wasn't really the fact that he had to kill his own son, but the fact that his son was the man who had brought them here. But what said the man next was just as shocking.

\- "There is only one way to get rid of the curse…Please destroy the moon."

/- The next day -/

Tha group was exploring the forest of the island. Last night, they were talking about finding a way to get rid of the curse without having to destroy the moon. Sento had thought about it all night and was still going.

 _"I'm 100% sure that the curse came from the island and not the moon. I concur, the moon does have a pole in that since we have to find why she is purple on this island and her presence at night transform the inhabitant. But the source of the problem is somewhere else. Also, I have a feeling the villagers are hiding something. If that moon was really the problem, why aren't already changing, even partially ?"_

As they were walking, they camed across a strange creature. A giant rat wearing a maid costume. When it attacked, it sprayed some kind of smelly gas before chasing the group.

 _ **ICE MAKE FLOOR !**_

The ground froze thanks to Gray magic and the giant rat slipped on it, falling and ending up knocked out. While running, the group had reached some kind of temple and entered it. Once inside, they saw moon shaped marks on the walls.

 _"Everything seems to turn around the moon here. But the curse just came a few years ago. Something had to trigger it, but what ?"_

Just then, thanks to Natsu, the ground broke, opening a hole and Natsu, Gray, Lucy and Happy, who managed to stuck a bone in his fell in it. Sento looked at the hole and wait.

…

*Thud*

Hearing them touch the ground, he took out a notebook.

"If the gravitational acceleration in this world is the same as in our world, which mean about 9.80 m/s², since the fall last for 5 seconds, then according to Newton's 'Mathematical Principles of Natural Philosophy', they must have fall for about 125m with a top speed of 50m/s, or 180km/h. Good thing people in this world are sturdier than in mine."

With that he took out two bottle and changed before going after them.

/- In the hole -/

He met with the rest of the group in some kind of hidden cave, wearing the Trial form TakaTank, having used the Solstall Wings. When they followed the cavern they reached something no one expected.

A gigantic monster, stuck in a huge ice sphere. While the group was trying to understand what this monster was, Gray seemed to know the answer.

\- "DELIORA ?!" shouted the ice mage, grabbing his friend attention. "Impossible ! How It can't be here ! It's, It's …"

\- "Gray ! Calm down and explain what that thing is to us ok ?" said Sento.

Gray then explained that this monster was Deliora, the devil of misfortune and disaster. His explanation was cut short when 2 men appeared. One was wearing a long vest with the biggest eyebrows ever, and next to him was some kind of … man-dog ? Shirtless with a collar, a dog face and dog ears.

\- "Daytime… I'm sleepy…" said eyebrows. Before turning to dog-face. "Did you get some moon drip on you ?"

 _"Moon drip ? Is it the name of the curse ?"_

\- "I didn't ! " snapped dog-face. "It's just decorative ! You should know !"

\- "I'm just teasing you, idiot."

\- "Yuuka-san, Toby-san, I have sad news." Said a third voice, feminine this time.

\- "Sherry." Said eyebrows, the man named Yuuka.

\- "Angelica was harassed by someone…" said Sherry

\- "It's just a mouse !" snapped dog-face, aka Toby

\- "She is not just a mouse… Angelica is a hunter that gallops the darkness. And love." The girl looked like some kind of gothic Lolita, with a skirt and thigh-high boots, some kind of long gloves, her curly hair tied into 2 ponytails. "Moonlight would gather soon… But how sad this is…" She then turned to her partners. "Let's get rid of them before Emperor Zero hears about it. Yes… Before the moon shows herself."

Once they were gone, Gray keep on explaining about Deliora. Apparently, that devil had penetrated the isbin area 10 years ago and was sealed in an iceberg by Ur, Gray's master, scarifying her own life in the process. It seemed like Gray was taking this personally. To the group, there was a question that kept coming back : why would someone bring that devil here if he was sealed on the northern continent.

\- "Whatever they want to do with this devil, it's linked to that moonlight they want to gather. Let's stay here until we saw what it is." Proposed Sento.

A few minutes passed and, bored, Lucy decide to make the wait more agreeable.

 _ **OPEN A DOOR TO THE LYRE ! LYRA !**_

Out of nowhere came out a young cheery girl with a big lyre on her back.

\- "Kyaaah ! I haven't seen you in ages, Lucy !" she said, smiling broadly. "What do you want me to sing today ?"

\- "Anything. It's your call."

Lyra then began playing and singing and it hit Sento hard. As if he had no control of his brain, he began replaying memories of his past. All the great moment he had with his friend. It brought some tears to his eyes.

 _"Wow, she know how to reach someone soul."_

The song was so emotional that Gray started crying, which he vigorously denied.

Later, as the group was sleeping, they heard a rumbling noise and the roof above Deliora opened and light began to shine upon the frozen demon. Going up the stairs used by the 3 persons from before, they followed the light and found a group of cloaked men gathering the moonlight.

-"I see, I know what's going on." Explained Lyra, who for some reason was still here. "They're going to use the moon drip to revive the devil !"

This shocked the group, and particularly Gray. And according to Lyra, the moondrip is so strong when gathered in one place that it could contaminate the human body.

 _"So I guess we found out why the people in this place are mutating."_

Then, a big man wearing a large mantle and a horned helmet arrived, followed by Yuuka, Sherry and Toby. It was that Zero guy. For some reason, Gray reacted strangely to the guy voice.

\- "Isn't Deliora revived ?" he asked

\- "Probably today or tomorrow. " Answered Sherry.

\- "About the intruders, I don't want anyone to get in the way. Only the village on the other end of the island has human there. Go and obliterate that village."

With that, the 3 colleagues rushed to the village. Natsu, deciding he had enough, blow fire into the air, drawing everyone's attention.

\- "We are the ones to stop you !"

Now that Natsu had done that, only god knew where it would end. Sento took the same bottles as before, and morphed.

 _ **TAKA ! TANK ! ARE YOU READY ?**_ "Henshin !"

Gray, looking like he lost it, rushed at Zero, sending a big wave of ice spikes to him. To the group surprise, Zero counter it with the same kind of magic.

\- "Leon. Do you know what you are doing ?"

Apparently, Gray and Zero, whose real name was Leon, known each other. Natsu, trying to rush at him, was suddenly freezing. Seeing that, Happy took Lucy up in the air and Sento took off with the Solstall Wings.

\- "Happy ! Why are you abandoning Natsu ?" asked Lucy, worries for the pink haired mage clear in her voice.

\- "He filled the space with chill magic !" he explained. "If we stayed, we would've been caught in the ice as well."

\- "But then…Natsu will…"

\- "Who will protect the village if all of us were taken ?" Sento asked Lucy, making her realize why Happy had done this. At that and seeing the tears in the small cat eyes, she apologized.

\- "Sorry Happy. Well then lets get to the village ! I'm sure Natsu can take care of himself."

\- "Yeah, we have to find a way to protect them." Said Sento

/- Later, at the village -/

\- "That's the worst plan I have ever seen in my life." Said Sento, a hand on his face.

When Lucy said she had a 'good' plan to stop Leon's men, Sento had hope. But now he was just dumbstruck at the sight of what it was : a pit fall, just behind the gate. It's true that it was the only entrance, but Sento and all the villagers had a feeling that fi someone wanted to come to destroy the village, a pitfall was nothing. When they heard that someone was approaching the gate, Lucy asked to opened it, 'hoping' to find the three bad guys but instead, it was Nastu, stuck in a huge ball of ice, and an unconscious Gray on his shoulder. He walked toward… right into the pitfall.

 _"My brain, it hurt. So much stupidity."_

When the team was once again gathered, they saw something in the air. The huge rat from before, flying by using his tail as a propeller, carrying a huge bucket. A small drop of the content fall toward Lucy. It was looking like jelly but Natsu tackled Lucy out of the way, making the drop touch the ground, making a hole around the impact point. It was acid. The rat, following Sherry's order, throw the acid jelly to the village. Natsu jumped to igniting his hands.

 _ **KARYU NO KOEN !**_

He join his hands, creating a huge explosion of fire, the shockwave scattering the jelly. The three mages were now on the ground, ready for a fight. The first to make a move was Sherry, calling her rat who dive to pick up the gothic, Lucy grabbing the beast without really knowing why. Looking at the rat in the sky, the group saw it suddenly falling to the ground. Natsu send Happy to look for Lucy before turning to Toby and Yuuka.

Natsu used his fire, but strangely, it didn't have any effect on Yuuka.

\- "Toby, don't butt in." Said Yuuka. "I'll take care of him myself."

Yuuka then send a wave to Natsu, who dodge it while he was ready to counter the attack.

\- "So you noticed its nature." Said Yuuka. "Each vibration I create nullifies all the magic. Which means…"He threw 2 big vibration at Natsu. "Mages are powerless in front of me !"

Natsu dodged and rushed at him trying to punch him with his fire. Yuuka surround himself with one of his vibration so Natsu's fire would be blocked.

\- "Then I won't use magic. See, i went through."

Indeed, his ar'm was inside the barrier, but he suddenly shout in pain.

\- "Thrusting your bare arm in a magical sphere is just rash." Said Yuuka. "You'll be blown away into pieces."

But then Natsu dived in, putting his head inside the barrier.

\- "I can't use magic inside the barrier. But I can use it outside, right ?"

With that he ignited his elbow, using the flame to propel his arm forward.

 _ **KARYU NO ENCHU !**_

With that boost, his hand reached Yuuka, punching him in the face and knocking him out.

With Yuuka down, Toby was the only one left.

 _ **PARALYSIS NAILS : MEGA JELLYFISH !**_

\- "There is a secret hidden in these nails." He said, his nails growing to become claws.

\- "Paralyzation ?" asked Sento, stating the obvious.

\- "How'd you know !?"

At that, Toby rushed at Natsu, trying to get him with his claws. But when he saw Sento, he stopped.

\- "Hey ! You have one of those bottles too ?"

What he said surprised Natsu and Sento. That idiot had a Fullbottle ? And indeed he had. Reaching into his pocket, he took out a white Fullbottle. He then began to use its power, encasing his hands in huge white Wolverine-like claws.

The Panda Fullbottle.

Sento, still in his TakaTank Trial Form, walked to Toby.

\- "I'll take that bottle back."

Pulling out two bottles, he switched form.

 _ **NINJYA ! COMIC !**_ _ **BEST MATCH ! ARE YOU READY ?**_

 _"Did he said ninja ?"_ though Natsu.

"Build Up !" _**SHINOBI NO ENTERTAINER ! NINNINCOMIC ! YEAHHHH !**_

Now, Sento was wearing a purple and yellow armor. The yellow part had an eye shaped like a pen drawing a comic, small comic panel on his chest and pen like protection on his shoulder and hand. The violet ninja part didn't have anything special, with the exception of the shuriken shaped eye. Then out of nowhere, a sword appeared. It was purple and yellow and the blade was composed of 4 comic panel, each one describing a power. The 4Koma Ninpoutou.

Toby swung his arm at Sento, but Sento dodged and pressed the trigger on his sword once.

 _ **BUSHIN NO JUTSU !**_

Then, colorful lines came out of the sword, creating clones of Sento. The whole group rushed at Toby, while Sento pressed the trigger again, 4 times now.

 _ **KAKUREMI NO JUTSU ! DORON !**_

He then disappear completely and after sometimes, the clones disappeared, but what confused Toby the most was the fact that his white claws weren't there anymore. He then heard something behind him.

 _ **FUTON NO JUTSU ! TATSUMAKI GIRI !**_

By the time Toby understood what was happening, he was sent into the air and disappeared. Sento, using his invisibility spell, was behind Toby and took the Fullbottle from him and he didn't realized it. Unmorphed and realized that Natsu wasn't there anymore, Sento decide to try to find him when…

\- "Where do you think you are going ?"

That voice, Sento recognized it and it send shiver down his spine, as he began sweating, turning to be face with a red haired monster a sword pointing at him.

\- "E-Erza. What a pleasant surprise !"

He tried to smile, to do it friendly, but when he saw the kind of look she had in the eyes, he knew that whatever he could say, It wouldn't change the outcome.

He was dead.

 **OK. It was a smaller chapter than the last one. But it would be far too long to do the whole Galuna island in one go. So I decided to split it.**

 **Next time : Titania is here ! A fight between old brothers. The return of a demon and the truth about the villagers.**


	11. Chapter 11 : Ice fight & Galuna's truth

**Ok, let's get going with our story without further ado.**

 **I don't own Kamen Rider or Fairy Tail.**

 **P.S. : i'm publishing 2 new chapterat once because i forgot to publish the 10th, sorry.**

 **Chapter 11 – Deliora and the secret of the island**

 _Italic : Sento's though_

/- Galuna Island village -/

\- "Erza !"

Gray's surprise was basically what they all felt when they saw Erza for the first time on the island. She was now seated in a tent, in front of Gray who just arrived with Sento, Lucy and Happy all tied up with ropes on their knees next to the knight.

\- "Weren't you supposed to stop them, Gray ?" asked the redhead, eyes closed. "I'm too shocked to say a word."

\- "W-Where's Natsu ?" asked Gray.

\- "That's what I'd like to know." Answered Erza finally opening her eyes.

\- "We were busy fighting those guys who attacked the village. But when I finished my fight, he was already gone."

\- "So it mean that Natsu is still wandering around without knowing where to go." Said Erza while standing up. "Gray, we're going to look for Natsu and as soon as we find him, we're going back to the guild."

At that, Gray looked unsure.

\- "What are you talking about, Erza ?" he asked. "If you heard our story, you should know what's going on at the island, right ?"

\- "So what ?", she asked, dead serious before saying "I came here to bring back whoever broke the guild's rule. I have no interest in anything else."

\- "I'm disappointed in you… Erza." Said the ice mage, shocking us all. It was not something to say to Erza.

\- "What ? Are you going to break the guild's rule ? " she said, pulling out a sword, pointing its tip at Gray's throat. "You won't get away unharmed."

Gray surprised the group once again, by grabbing the blade, even cutting his hand in the process.

\- "Do whatever you want ! This is what I chose !" he said, looking directly into Erza's eyes. "I just got to do what I got to do."

Erza lowered her sword, Gray began to leave and turned back to say one last thing.

\- "I'll do what I want till the end. Cut me down if you want."

With that, he left and Erza, pissed off, turned to the three restrained persons, who began to fear for themselves.

\- "E-Erza, c-calm down !" said Lucy

\- "Don't let that anger consume you ! "said Sento.

But instead of hurting them, Erza cut the ropes, freeing them.

\- "This is absurd." She said without turning. "We'll take care of it after this job."

And whit that, they met with Gray, and head to the temple.

/- Eat the temple -/

\- "The ruins are… tilted ?"

Lucy's comment could have been considered stupid if the ruin weren't really tilted. It was like the ground became unstable and swallow a part of the base.

\- "Well, since the ruin are tilted, it means the moonlight can't reach Deliora anymore." Sento said.

But the group was found by the wizard who were praying to gather the moonlight. Erza staying behind to take care of them, the rest kept going toward the temple. When they reached the temple and went inside, they found huge wall of ice blocking the way. It was Leon's work and when Gray opened a hole inside, he found Natsu fighting with Leon.

\- "Natsu, let me take care of him."

Despite Natsu's contestation, Gray stood in front of his old friend.

\- "It's my fault if Ur 'died' ten years ago…", he admitted before continuing. "But I won't forgive for hurting my comrades, the village and trying to melt the ice."

He then took a stance, both arms stretched in front of him, crossing, in a posture that Leon recognized and didn't liked.

\- "That posture… Iced Shell ?! Have you gone mad !?"

\- "Iced shell ?" repeat Natsu and Sento.

 _"Isn't that the magic used by Gray's master to froze Deliora, scarifying her life in the process ? He is bluffing, there is no way is going to do it."_

\- "Return the people of this island back to normal then take your comrades and leave." Gray asked. "This is your last chance."

\- "I see. So that was just a threat… Ridiculous." Answered Leon with a grin.

But when Gray began to gather is magic, blowing everyone away, they knew he was serious.

\- "The fact that Ur died because of me will never change, regardless of how many years have gone by." He said, ice appearing on his body. "I need to take responsibility one way or the other." Looking up, he then conclude. "The time has come. I'm prepared to die." He then shout, asking one last question to Leon.

\- "Do we die together … Or live together !?"

\- "Do it. You don't have the guts to die." Was Leon answer, pushing Gray to the limit.

\- "You disappoint me." He said calmly before he began to invoke his spell. "This is the end !"

 _ **ICED …**_ "FOOOOOOOOOOOOOOL !"

All of a sudden, Natsu had came and punched Gray in the face, preventing him from using the spell who would have cost him his life.

"Nice one, Natsu ! At least, you care a little for him, I was starting to have doubt." Though Sento with a smile. But then…

\- "Don't just barge in out of nowhere to start rambling about responsibility and all." He said, clearly not amused by what Gray just did. "This is MY show."

 _"… I take back what I just said."_

Gray, after after recovering from his surprise, jumped at Natsu, grabbing him by his scarf, clearly not amused.

\- "I have to put this thing between Leon and me to an end !", he said. "even if it means I have to die for it !"

Natsu stopped him by grabbing the arm holding his scarf and said, a deadly shine in his eyes.

\- "So you're gonna end this by dying, huh ? Stop running away."

At that, Gray calmed down but soon, they heard a rumbling noise. Soon, the temple was shaking like there was an earthquake. The tremor quickly stopped but when it did, the temple wasn't tilted anymore.

\- "What ? How can the temple be back in his original position ? It's like he never moved ?" asked Sento, not understanding how that could have happen. Then a cloaked man appeared, wearing a cloak and a strange mask.

\- "Zarti, it's you who put the ruins back in place ?" asked Leon.

\- "It took me so long to tilt them." Said Natsu. "How did you do that ?"

\- "Ho Ho Ho" was all he got as an answer, so Natsu asked again, shouting this time.

\- "HOW DID YOU DO THAT ?!"

\- "Now, let me go start the moon drip ritual." Said Zarti, turning away, ignoring Natsu, who didn't like it one bit.

\- "… AHHHHHHHHHHH ! WAIT UP YOU BASTARD !" shouted the salamander while chasing after Zarti. "Gray, I'm gonna take care of that guy. You take care of Leon !"

And with that, he disappeared inside the temple. Now, Gray turned to face Leon once again, but the mood was slightly different. Sento then though about that Zarti.

"This guy is strange. What kind of magic does he have to be able to repair a whole building and put it in the exact same state as before ? And why does HE want Deliora free ? That guy is suspicious."

When Sento returned to the discussion between the two ice mage, he just had time to understand from what was said that iced shell was useless on this island since the ice could be melted by the moon drip.

\- "Let's stop. Gray suddenly said, shocking Sento and Leon. "Give up on Deliora."

\- "What is this nonsense you're spewing ?"

 _"Leon is right. First a threat, now a persuasion, Gray is not making any sense. What is his goal ?"_

\- "Leon, Ur is alive." He said, surprising the two other again. "Iced Shell transform the user body in ice. The ice that sealed Deliora, that you are trying to melt is Ur. She is still alive as the ice." Leon, head hung low, walked slowly toward Gray as the latter was apologizing to have kept the secret.

 _"I see, so that's how it is. Does that mean that Ur's consciousness is still in the ice as well ? Does she know that one of his pupil was melting her to kill the devil ?_

Suddenly, Sento was pulled out of his though by a disgusting noise : the noise of a blade piercing a body. Looking up, he saw Leon, an ice sword in his hand, sunk to the hilt in Gray belly, blood coming out of his mouth. But what was the most disturbing to Sento was Leon's face. It wasn't the face of a mage. It was the face of a demented.

\- "I already know all that. That's not Ur anymore. Just scrap of ice."

When Gray fell on the floor, holding his wound with his hand, Sento couldn't just stood on the side anymore.

\- "Don't tell me you seriously believed that Ur is alive, right ?" asked Leon. "Grow up already."

\- "You knew it… But still did this…" said Gray, anger clearly painted on his face, panting because of his injuries.

\- "Let's put an end to that shall we ?" said Leon, pulling out another ice sword, ready to swing at Gray. "Good bye, Gray."

 _ **FUTON NO JUTSU ! TATSUMAKI GIRI !**_

A tornado suddenly appeared at Leon's feet, throwing him into the air, droping his weapon. When he land, he turned to see Sento in NinninComic form, the 4Koma Ninpoutou his one hand.

\- "Not on my watch." Simply said Sento

As Leon was ready to attack Sento, he was punched suddenly in the face by Gray, the latter with a dangerous glint in his eyes.

\- "Impossible ! How can you move with that injury !?"

 _"Indeed, being pierced by a sword is not something you can recover from so quickly."_

\- "I'm fed up…" said Gray, curiosity making its way on Leon and Sento's faces. "I wanted to save you. But I'm fed up with it."

He suddenly create a bow, and shot 3 ice arrows at Leon, sending him to the ground. Leon didn't have enough time to get up when Gray sent a kick directly into his face, sending him to the ground once again. Gray then unleashed hit after hit, chaining kicks, punches, headbutts. The Fairy Tail mage was literally destroying his old comrade.

\- "Gah, I can't be bleeding… Because of GRAY !" he said while leaning on a wall for support before striking back.

 _ **ICE MAKE : SNOW DRAGON !**_

A big dragon with a snake like body appeared and bit Gray, sending the latter to the ground. Suddenly the ruin began to shake.

 _"It's probably the moon drip ritual. But wait, who is praying up there ? I though Erza and Lucy were taking care of those guys ?"_

While Sento was thinking, Gray and Leon kept fighting, exchanging blow after blow, when Leon rushed at Gray, an ice wolf head forming on his hand.

\- "Now that our teacher is dead, think carefully of how her left-behind pupil can do to surpass her !" said Leon. "With Deliora ! I will surpass Ur by defeating Deliora, which is the only thing she couldn't do !"

\- "Your aspiration is admirable, but you failed to notice that you chose the wrong path." Said Gray while dodging Leon and his ice wolf. "Someone so blind is trying to surpass Ur ? You're 100 years too early for that. Game over, try again !"

With that, he slashed at Leon with an ice sword, only to destroy an ice clone, the real Leon behind him.

 _ **ICE MAKE : SNOW TIGER !**_

Leon threw a huge tiger made of ice at Gray, who jumped above it.

 _ **ICE MAKE : PRISON !**_

Grey create a huge cage of ice, trapping the beast inside.

\- "Is that all you've got, Leon ? Such a pitiful beast." Taunted Gray getting off the cage.

\- "Ridiculous ! I'll just smash your molding magi…"

But he couldn't. Gray's prison was too strong for Leon's tiger.

\- "One-handed molding is unbalanced. That's why you are incapable of using your full power at important times." Explained Gray, forming something with his ice, Leon shocked by what his old comrade just said. For Sento, it was pretty clear.

Gray had won.

 _ **ICE MAKE : ICE CANNON !**_

In Gray's hand was a huge cannon made of ice, who shot a huge bullet of ice at Leon, sending him in the temple walls.

\- "That's what Ur taught us." Finished Gray, before Leon fall to the ground, knocked out. Gray fell to his knees, his wound opening again. Sento reached him when he just finished patching himself with ice when a deafening roar made the walls shake. That could mean just one thing.

Deliora was free.

When Sento saw the look in Gray's eyes, he knew what he wanted to do and stopped him.

\- "Wait. You intend to use Iced Shell isn't it ?" Sento asked while grabbing his arm.

\- "It's the only way to stop Deliora. So I'll do it."

\- "And I'll stop you if you try." Countered Sento, surprising Gray who was about to retort when Sento cut him. "In my life, as a scientist or a Kamen Rider, I have always faced problem who seemed to have just one possible outcome, and I met a lot of people, myself included, who were ready to choose that outcome even if it meant huge sacrifice. But, there was always a way to solve everything, without losing anyone, but always crazy. One of my fellow Kamen Rider died one day, and his friend tried and succeed in doing the impossible to bring him back. For that, they had to fight against despair, sadness and all the odds that were against them, but they succeed. There is a way to stop Deliora without using Iced Shell, and it's something you think impossible."

\- "And that is ?" asked Gray.

\- "We destroy it."

As Gray was trying to assimilate what Sento just said, Deliora was in view, fully awake, Natsu just in front of him. Leon, who crawled up to here, with that demented look in his eyes, was trying to stood up, hoping to fight and beat the beast even though he was a mess. But as soon as he was up, Gray hit him in the back of his neck, knocking him out.

-"That's enough Leon. Leave it to me." Said Gray, before taking a know well known stance. "I'll seal Deliora !"

But as he was starting to gather his magic, Sento and Natsu stood in front of him, facing Deliora.

\- "We'll fight it." Said the Rider and the Salamander at the same time.

\- "Move it ! You're in the way !"

\- "I stopped you earlier because I didn't want you to die. Didn't my voice reach you ?" asked Natsu, Gray slowly stopping his casting. "Go ahead and use that spell if you want to."

\- " I already told you, Gray." Completed Sento. "There is no such thing as 'there is only one way.'. We'll destroy that thing. And to be honest, it's not my first time fighting against giant." He finished with a smirk taking two Fullbottles out.

But when Deliora lift his arm in an attempt to strike the group, something no one expected happened. His elbow cracked and broke like stone and soon, his whole body shattered, leaving just rubble where the devil once stood. The truth hit them, and mainly Leon, hard. Deliora was already dead, subverted for ten years in Ur's ice. With the devil dead, it was now time to help the villager with the reason they came here in the first place.

Everyone was gathered in the cave and they were happily congratulating themselves for succeeding in doing a S-class job. But Erza wasn't so sure. While they all though they were going to die, what she said wasn't really what they expected.

\- "The job isn't finished yet. The true goal was to help the villagers turned into demons." She said. And it's true that they had to find a way to help them, but even Leon wasn't able to help them. Apparently, they never saw any of the villagers in the three years they spent here.

"How could the villager have never investigated the temple ? I mena, for three years every night the moon shone on it, so why ? Also, Leon, Yuuka, Sherry and Toby spend three years here and they haven't been affected by the light. I have a feeling those villager are hiding something."

\- "Let's head back to the village, we will see here what to do." Said Sento, before they all head back to the village.

/- Later, in the village -/

Back at the storage place of the village, they found no one, like they all disappeared. Until one of the villagers came running to them.

\- "Hello sirs ! You're back ! It's really worrysome ! " he said, while no one understood why he seemed so tense. "Anyway, please hurry to the village !"

Back at the real village, they realized that everybody was here and that the village that everybody thought was destroyed was back to its former glory, like he never was destroyed.

 _"What happened ? It magic for sure, but what kind ? Wait, it's like time rewind itself to a period where the village was in one piece. Isn't that what happened when the temple was tilted then put back in place ? So that cloaked man was behind it ? Why would he do that ?"_

Later, Erza had gathered all the villager to confirm something. They said that their mutation began when the moon turned purple three years ago. She began to think about all that, the fact that they never saw the light from the temple, or things that seems obvious. She was so deep in her though that when she fell in Lucy's pitfall, who was restored too, she kept going, concluding thatthis village was the strangest place of the island. Then she asked a question.

\- "Why didn't you investigate it ?"

\- "T-that's because… It's a tradition not to go anywhere close to the temple…" answered the mayor, but judging bt his hesitation and the villagers murmur, he wasn't sure himself. Then they told the truth : they tried to investigate, but they could never get close to the ruins. Each time they tried, even by walking straight toward the temple, they ended always by the village gate. Hearing that, Erza took a decision. She changed her armor, taking the Giant's armor who increase the throwing power and took out the Evil crushing Spear, a spear who subdue darkness, in one hand and asked Natsu :

\- "Natsu, help me. We are going to destroy the moon."

\- "WHAAAAAAAAAT ?" was basically the group reaction at what the knight said.

Natsu and Erza took position. Erza began to swing to throw the spear when Natsu hit the end of the spear with his fire punch. The spear took of at a blinding speed and flew to the skies. It flew high and after some moment, the moon began to crack, to the joy of the villager and the shock of the mages. But Sento knew something was wrong.

\- "They didn't reached the moon."

\- "Huh ?" said the group, not understanding.

\- "The moon is too far. I know Erza and Natsu are strong but it's way too much, they can't do it."

\- "But then, what are those crack ?"

Soon, the cracks kept expanding…. And left the moon to crack the skies. And soon, the cracks kept going until the shy began to fall shattering to pieces. But it wasn't the sky, it was the crystal like layer above the island.

\- "I see. It's basically the same as greenhouse gases." Understood Sento.

\- "What do you mean ?" asked Lucy, her eyes still on the falling 'sky'.

\- "It means that the moon drip created some kind of exhaust fumes. Those gas crystallized and form a dome like layer between the moon and the skies, giving the impression that the moon was purple; it was because we were looking at it through purple glass."

\- "Then now that the layer is gone, the villagers will become human again." Said Lucy, turning to the townspeople with a smile, before realizing that they still were demon. Then it dawned on them suddenly : those villagers were demons from the beginning. The moon drip was altering their memory, making them think they were humans because they could change into ones. That's when Bobo, the now fully demonic guy who brought them here, appeared to be reunited with his father again. Once the surprised passed, the demons took off, flying away in the night, putting an end to the curse of Galuna Island.

OK, that's done. I hope you liked it. Don't hesitate to review if you have any suggestion for the story.

 **Next time : Wrecked guild and beaten up comrades : It is war ! Fire meet Iron ! The missile and the cannon ! Why is Lucy a target ?**


	12. Author note : i'm stopping

Hello Guys. I'm really sorry but I'm gonna stop this story.

I know that some of you liked it and i'm really sotty to disappoiint them, btu i realized 2 things :

\- It took a lot more time than i though, and between my job, the stories and everyything, i was having trouble to manage everything. So since i can't keep up, i'm stopping everything.

\- I realized that my story was too much like the Fairy Tail stroy, i basically feel that i'm dopying it most of the time. And when i look at some chapters, i'm not really proud of that.

I'm sorry again but i'm stopping this story. Maybe one day, it'll come back,but it won't be soon. And i'm not abandoning fanfictions. I'll write new stories but they will be shorter, like one shots, and i'm giving myself time to think about what i should make.

Concerning this story, there mlight be a way to keep it alive somehow : i'll write a new story, starting where i left this one but focusing on the main events : finding bottles, best matches, important moments for Sento etc. If it's okay with you, i'll do it.

Sorry again and thanks for your support.

Erzats


	13. Author note : i'll try again

Hello guys.

After thinking about it, and seeing that there are many people who seemed to like that story, i'm gonna try it again. I know it seems like i don't know what i want, and it's kinda right to be honest, but i'm gonna try to make that story last.

Furthermore, if one day i decide to abandon the story, i'll put it for adoption, in case someone would like to take it over.

The 12th chapter will come by next Sunday, but there is a chance that it will be before. As for the updates, i'll try to make at least one by week. And concerning the story, i'll be focusing on some part, so there might be some moment i'll pass.

Hope you'll like what i have in stock.

Thanks.

Erzats


	14. Chapter 12 : Phantom Lord

**Ok, Here is the 12** **th** **chapter, marking the beginning of my return. I know it was not a big pause, but I made some choices. Concerning my updates, I'll try to do one by week at least but don't be surprise if it's more. Just know that for the moment, I won't abandon that story.**

 **Also, it will be more Sento-centric, so some events won't be fully described. Sorry for that if I miss events you love.**

 **As for FanFictionHunter questions, basically, the items will appear in the same order as in the show. As for a Super Sentai crossover, it gave me ideas, and it could come sooner than you though, even if the explanation for their presence might be a little easy.**

 **I don't own Fairy Tail and Kamen Rider**

 **Chapter 12 : Phantom Lord**

 _Italic : Sento's though_

After the events on Galuna island, the group of mages just entered Magnolia. Since they just succeed in doing a S-class job and they were quite proud of it, but when they remembered that they weren't supposed to do it, since they weren't S-class mages. While they were busy guessing what kind of punishment the master had for them, Sento noticed that the townspeople were looking at them, while whispering between them. What Sento didn't like was that their eyes and voices looked like they were talking about people who just lost someone. And when they reached the guild, they knew why.

\- "What the fuck happened, here ?"

It was a legitimate question from Gray because the guild was wrecked. Huge pillars of metal were sticking out of the walls and roof. The guild flags, in shreds, and the board where the name was written was broken. The group was shocked and anger began building up in them, wondering who would dare to do that.

\- "Phantom." A single world answering their question, given by a well known voice coming from behind them. "It's mortifying… But we were done in.." said Mirajane, her usual smile gone.

The barmaid guide the group to the guild 1st floor basement, where they found the rest of the guild. It's seemed like no one was hurt. Or at least not physically. Also, they seemed to discuss about what to do : some were ready to go to Phantom Lord, the guild who wrecked the guild hall while other were more reserved about it. Apparently, this guild was a powerful one. As for Makarov, he was drinking a beer sitting cross-legged on a barrel, seemingly drunk and not giving a shit about what is happening.

\- "Ji-chan ! This isn't happy hour, is it ?!" roared Natsu, clearly not happy to see the master not fazed by what had happened.

\- "Oooh, right you are." He said before a quite angry expression appear on his face, but not for the reason they though. "Guys ! How dare you go on an S-class quest without permission !?"

"What ? Is he serious ?"

\- "Punishment ! I'll give you your punishment now ! Prepare yourself ! " he said with a mighty voice, raising his hand.

With that, he stretched his arm, hitting the culprits on their heads with a "Bad !" each time, but slapping Lucy's ass instead of her head.

\- "Master ! Do you understand our current situation !?" said Erza, having enough of it.

\- "They wrecked our guild !" shouted Natsu, looking more angry than never. Apparently, touching his 'home' was the last straw for him.

\- "Well, calm down." He finally said, serious again. "It's not something to make a fuss about."

\- "What ?"

\- "Phantom, right ? This is as far as those idiots will go." He said taking a sip of his beer. "I don't see why they even bothered attacking an empty guild."

 _"For the guild to be empty, they probably have done this in the middle of the night. That explained why no one is hurt. But why would they attack an empty guild ?"_

\- "There's no need to cross with someone who resorts to surprise attacks. Leave them be." Continued Makarov, but Natsu was not thinking the same.

\- "I can't accept it !" said Salamander. "I won't feel right until I swash them down !"

\- "Natsu ! Cut it out !" answered the master with the same voice stretching his arm to slap… Lucy's ass again.

\- "AND STOP TOUCHING HER BUTT, YOU OLD PERVERT !"

\- "Hum ? Why is that bothering you, my boy ?" asked Makarov, a mocking grin on his face.

Natsu, realizing what he just said, turned his head in a childish way, crossing his arm, his cheeks red. Makarov stood up to go take a piss and Erza explained to Natsu that if the master didn't want to fight back, they had no choice but to do the same. Sento had a feeling that it was just a beginning and head back to his home.

/- Magnolia's Street -/

Sento was sitting on a bench near the main park of Magnolia, his phone in his hand. He was giving the final touch to the upgrade he made, using the device he got from some Shocker member during the Lullaby incident. Now that it seems ready, he tried to call Ryuga.

*Riiiiiiiing, Riiiiiing*

After some times, someone picked up.

\- "Ryuga. Who it is ?" answered Cross-Z

\- "Yo Ryuga, it's Sento. How are thing going for you all ?"

\- "Well, quite good, we've found…" He then stopped, as if his brain was processing what that phone call meant. After a few minutes, he replied. "Wait ? SENTO ? IS THAT YOU ?"

\- "Who else could it be, idiot." Replied Sento.

\- "But how ?" asked the dragon Rider, whose shout drawn the attention of everyone around him.

\- "Let's just say that I used some of what Shocker have." He said, before continuing. "So, as I just asked, how are thing on your side ?"

\- "Well, according to what we found by looking in Shocker's files, we have some news for you. " Said, Ryuga, looking at the research results he had in front of him.

\- "I'm all ears."

\- "Ok so first, what kind of world are you in ?" asked Banjou.

\- "A magic world. A world of mages, spells and curses. Not my kind of things as you probably know." Answered Sento, standing up from the bench he sat on and began to walk in the streets.

\- "So that's why Haruto felt strange near that portal."

\- "What do you mean ?" asked Sento, not understanding what Kamen Rider Wizard have to do with all this.

\- "The portal on our side was covered in some kind of unknow energy. It seems like Shocker made some research on it, as if they tried to understand how to use it."

\- "They were sure that energy was from that other world and learning how to use it was a natural thing to do if they wanted to come here. That might also mean that they already have some way to combine their technology with magic, or at least interact with it. It's not good."

\- "Yeah, it's bad news if that's the case. Secondly, we managed to stabilized the portal."

\- "So you can use it ?" asked Sento with hope. It could mean he won't have to be the only Rider here.

\- "Well, yes and no." answered Ryuga. "The portal allow us to send you help, yes, but if it's a human or an animal, he won't be able to stay."

\- "What do you mean ? I'm here and I've never felt like I was sucked back into my home world.", said Sento, not understanding.

\- "Well, according to the brains we have over here, the living being of each world have a different kind of life force, or something like that, which prevent them from going into another world. If you jumped to another world, you'll be forcefully dragged back to your home world." Explained Ryuga before adding. "To make it more simple, we can send Riders or other people to help you, but it will be temporary, since they won't be able to stay."

\- "And if I can stay here, it's probably because the portal was somewhat upgraded by Shocker so THEY could stay and I took the opportunity by using what was left of that upgrade."

\- "But all is not lost. We're working on a way to stabilize the portal once again, so we can send someone to help you, but we are far from finished. But we have a surprise for you."

\- "Great." Said Sento, being sarcastic. "I can't wait to go home to see it since you can't send it." But then he processed what Ryuga said about the portal. "Unless the surprise is not someone but something ?"

\- "Yep ! We build here some kind of radar to help us found you thanks to your Rider powers and we are going to use it to send you something that will help you greatly, I'm sure."

\- "Well, if it's that great, I can't wait." Said Sento, hope growing in him.

\- "Ok. It's on the way. We put the instruction to use it inside the briefcase. Good luck, we'll call you if we found anything good." At that, Ryuga hung up and Sento saw a portal appearing in the sky above the city. Something fell out of it and it closed immediately after. Sento ran to where the gift landed and found a briefcase. Opening it, he found some kind of phone, red and blue with a big touch screen. Before he could even try it, he felt strange, as if something really bad just happened. Looking up, he realized that he was in front of the big tree of Magnolia Park, one of the symbol of the city. But what was on the tree make the Rider's heart stop.

Levy, Jet and Droy were here, covered in bruises and wounds that seemed really bad, blood flowing on their face, clothes completely shredded. A mark he didn't recognized was drawn on Levy's belly but judging by the iron shackles used to literally crucified them to the tree and what happened to the guild hall, it wasn't that hard to know what happened :

Phantom Lord had attacked again, and this time, they definitely crossed a line that shouldn't have been crossed.

Anger boiling inside him, he decided to alert the others. But since he also had to stay to keep an eye on them…

 _ **NINJYA ! COMIC !...**_

/- Later -/

A few minutes after Sento sent his Ninnincomic clones to find the master and the other guild member, they were all here, along with some citizen drawn by the commotion. Sento though he knew what anger, rage and fury were, but when he saw the faces of people like Erza, Gray and mainly Natsu, he realized he didn't knew that much. The crowd moved away as Makarov walked to the tree. He looked at the 3 mages he considered as part of his family before looking down, his face hidden in the shadow and slightly trembling, but it wasn't from sadness : it was from anger.

\- "Wrecking our shoddy bar I could bear with…" he said with a low but strong voice. "…But no parent can remain silent after seeing their children's blood…" As he finished, his grip on his stick-like cane became so strong it broke under the pressure. He then looked up, his face covered in the purest expression of rage.

\- "THIS MEANS WAR."

/- Oak, Phantom Lord Guild hall -/

Almost all of the Fairy Tail mages were here, standing in front of the Phantom Lord guild hall, a building looking like some kind of castle. The mages moved as if they were one, going straight at the door, a door Natsu destroyed with his fiery punch.

The face off began, the Fairies on one side, ready to wreck the Phantom. Sento was not surprised, but it was strange to see everyone one of the Fairy Tail mages with such serious expression on their faces. Soon, it began to fight everywhere, the Fairies clearly taking the advantage. But for Sento, who was currently in GorillaMond, something was strange.

 _"Where are the big ones ? They are supposed to have a dragon slayer and 4 mages with level close to Fairy Tail's S-class. They pushed to guild to its breaking point and the elite of their group isn't here ? I'm sure they knew we were coming, so why ?"_

Just then, a guy dove from the roof, using a big iron arm to knock several people, Fairies and Phantoms without distinction. That guy, long black spiky hair, red eyes and lots of piercing on his face, introduced himself as the Iron Dragon Slayer, Gajeel Redfox.

 _"So that guy has the same kind of magic as Natsu, but with iron ? I wonder what he can do ?"_

He began fighting Elfman, who caught his iron leg with his beast hand when the iron of Gajeel leg morphed, sending iron poles everywhere like a grenade sending shrapnel's, but with poles instead, striking his comrade along the way. As Elfman was sent on his back, Natsu jumped at Gajeel using Elfman as a footboard and punched the iron dragon slayer with a fire punch, sending him flying across the room.

They began fighting, but Natsu had the advantage, striking Gajeel without letting him breath, following him on the roof structure of the guild. Suddenly, everybody heard a rumbling noise and the whole building began shaking. While everyone in Phantom Lord, and even Sento, was confused as to what was causing this, the Fairies where all grinning.

\- "This is master Makarov's 'fury'." Explained Erza. "A giant's fury…no one can stop."

This revelation made every Phantoms shiver in fear, while Makarov was approaching Jose, Phantom's master. But a few moment later, the Fairies were in shock. Makarov fell from upstairs, his magic completely locked. Seeing Makarov in that state lowered the spirit of Fairy Tail, while Phantom was feeling a lot more confident. Erza knew this and decide it was time to leave.

\- "Retreat to the guild !" she ordered, everyone following the order, even if many of them were reluctant. As everyone was leaving, Natsu was suddenly tensed, as if all his worries were replaced by new ones. He the grabbed one of the Phantom and head to the exit, but not going in the same way as the others.

\- "Where are you going, Natsu ?" asked Sento.

\- "I'm going to save Lucy !" he answered without even turning his head, walking away.

 _"Save Lucy ? Did he heard those guys talk about her ? But why would they do that just for one person ? And why Lucy ?"_

Not having much of a choice right now, he decided to follow Natsu.

\- "Tell me where is Lucy ?" the fire mage asked the guy he was dragging along.

\- "I don't know… Who is that ?" he asked in return, before his whole body was set ablaze.

\- "Speak up." Began Natsu before lifting his head, looking like he was ready to kill that guy. "If Luce is hurt, I might burn you to a crisp."

 _"Luce ? Hhmmmm"_

\- "I… I don't know, really !" explained the poor burned guy. "But our headquarter is located on the hill straight ahead !"

Indeed, they soon saw a building looking like some kind of citadel, with a tower on each side. While it was still kinda far, the guys could see something falling from the top of one of those tower. Sento heard a noise but couldn't guess what it was exactly, but Natsu, thanks to his acute hearing, probably heard it better, since he suddenly rushed toward the toward, leaving Sento in the dust. Sento ran after the Dragon Slayer and when he was closer to the tower, he understood why. The falling figure was in fact Lucy, hands tied behind her back. The noise was probably her shout and Natsu caught her just in time, just before she crashes on the ground.

 _"Did she trusted Natsu so much she jumped from that height knowing he would be here to catch her ? So much trust, they clearly are a best match."_

As Happy and Natsu were fighting about what to do, the cat saying they should go back to the guild while the salamander wanted to fight Phantom since they were at their HQ, Lucy seemed to feel more and more guilty.

 _"What is that ? She look like she has something to blame herself for. "_

\- "Sorry… It's all…my fault…" she said, voice trembling and tears streaming down her face turning to the boys. "But I … still want to stay in the guild… I love Fairy Tail."

The guys didn't understood. Why was she talking like she might be forced to leave the guild ? Seeing her cry, Natsu fell to one knee and take her in his arms, trying to comfort her, showing to the Rider and the cat a side of him they've never seen before. Once Lucy had calm down, they head back to the guild, not knowing that the Phantom Lord HQ was changing shape.

/- Magnolia, Fairy Tail Hall -/

The air in the guild was heavy. Makarov was brought to Porlyusica by Alzack and Bisca hoping the old woman could heal him. In a corner, Lucy explained the situation to the guild. Her name was Lucy Heartfilia, only daughter and heiress to the Heartfilia family, a powerful and wealthy family and his father, her only relative left, a cold-hearted man, hired Phantom Lord to retrieve her. She also revealed that she ran away from her home to follow her dream of being and get away from her father.

\- "I'm really sorry…" she said, lowering her head. "Everything will go back to normal if I go home."

\- "Is that so ?" Natsu answered, grabbing her attention. "I mean, the term 'lady' doesn't really suit you does it ?". Said like that, it could have been mean, but he kept going. "You fit better in this dirty bar, laughing and merrily going out on adventures. You said you want to stay here. What good would it do for you to return to a place you hate ?" He was right, and his words reached Lucy's heart. "You are Lucy from Fairy Tail, right ? This is your home." As tears of happiness swelled in her eyes, they were all drawn to Kana and Mirajane. The card mage was trying unsuccessfully to find where Mistgun was and Mirajane was currently talking with Luxus with a communication Lacryma. The barmaid was trying to convince him to come. After all, without the master, Mistgun or that geezer as they were calling him, Luxus was the only one who could help them. But of course, he seemed more disposed to let them down than help.

\- "Lucy, our comrade is being targeted." Said Mira, in a new attempt to convince him, but of course…

\- "Huh ? Who's that ? Ah, that big-boobed newbie, huh. Tell her if che becomes my woman, I'll help out." Heat suddenly rose in the guild. "And tell that geezer to hurry up and retire so he can give me his posi…" He never finished his sentence. Natsu just punched through the lacryma, hate painted on his face. While everybody was trying to understand what happened, earth began to shake at a steady pace, as if…

 _"As if a giant was walking."_

Realizing that, Sento was one of the first outside and when he saw what it was, he could only think about one think.

 _"Where are the Super Sentai when you need one ?"_

In front of them, closing on the city was the Phantom Lord HQ, walking thank to huge mechanical leg, like some kind of insect. After some time, it stopped and the front opened, revealing a huge canon. The cannon began accumulating energy. As it was about to shoot, Erza ran forward, ex-quiping a heavily plated armor, the Herculean Armor.

"Wait ? She's not going to…"

And she did. As the cannon shot, Erza took the blast full on. After a few seconds, the blast was stopped and Erza flew backward, clearly not able to fight anymore.

\- "After Makarov, now Erza is unable to fight too." That voice belong to Jose, Phantom Lord master, talking through a microphone, addressing the guild. "You don't stand a chance. Hand over Lucy Heartfilia right now."

But of course, Fairy Tail was not disposed to give up, they'd rather die rather than give up on their comrades.

\- "Fine, we'll fire the canon once more if that's what you want." Said Jose clearly not liking that resistance. "Now struggle in this 15 minutes terror until it's reloaded !"

Then, what looked like an army of cloaked men jumped out of the guild and rushed at the guild, but it wasn't everything. Suddenly, the guild all began shooting what looked like bullets at the Fairies, exploding when they reached the ground. Seeing them closely, they looked like…

 _"Missiles ? Wait, does that mean…"_

Soon, it was chaos. Lucy was sent away by Mirajane under the protection of Reedus, the barmaid taking her appearance to lure Jose, Natsu flew to the guild to destroy the cannon before the next shot, followed by Gray and Elfman and while Sento wanted to go, he couldn't leave the other fighting those things alone with the rockets still coming. They fought the best they could, waiting for Natsu to succeed. As time was passing, the cannon was closer and closer to being fully charged when suddenly.

*BOOOM*

Looking at the Phantom guild, we saw the cannon falling in pieces, revealing that Natsu did it. But as they were relieving in their success, it was shortlived when the base moved again, taking another shape. This time, Sento wasn't feeling well.

 _"Seriously, it's a job for a Super Sentai, not a Kamen Rider."_

The base just became a gigantic robot, towering over the city. And as if that wasn't enough, the robot began moving his hand, drawing a magic circle. It was also a mage. Rigth now, Sento knew he had to go in that thing, but he couldn't let the other, they needed reinforcement.

 _"Wait. Reinforcements ?"_

He reached into his pocket, pulling out the gift from his friend. Turning it on, it looked like a normal smartphone, but the applications were specific, since there was one for every Kamen Rider.

 _"Let's see, I need a lot of people.",_ he though as he scrolled through the applications. _"One Rider won't be enough, I need more but if I read correctly the manual, I can use just one application or two at the same time, it won't be enough…"_ Then, he stopped scrolling, looking at one application that got his attention. _"Wait, it is … ?"_ Since he didn't have any other choice, he took a decision.

And launched the application.

 **OK, Cliffhanger guys. So I'm pretty proud of that chapter, I hope you will like it. Also, I hope you won't find the explanation about the portal and how to call help too simple, but I didn't felt like losing myself in complicated theories, so I'll keep it that way.**

 **Next Time : Here comes the reinforcement ! Chasing the elements to stop the mechanical mage ! Take off and slash the phantom ! Giant vs Giant !**


	15. Chapter 13 : The reinforcements

**Ok, guys, here come chapter 13. I hope you will like it.**

 **Before starting, I have to say that I saw your reviews and comment about the story and mainly about who is going to be call as reinforcement in this chapter. And I think it's not going to be who you though it would be. Also, I must say that I probably won't use the Reinforcement device much, unless I got THE idea. But I'll try to use it from times to times. Anyway, lets go !**

 **I don't own Kamren Rider or Fairy Tail.**

 **Chapter 13 : Reinforcements and giants.**

 _Italic : Sento's though_

The guild was still fighting the creatures from Phantom Lord, while Natsu, Grey and Elfman were inside the robot guild, fighting to stop it from casting Abyss Break. It was a tough fight, but as time goes by, the robot was slowing down, taking more and more time to drew the circle. Sento knew that Elfman took care of one of those guys, since he was basically in the open and had met with Mirajane, on the robot hand when the barmaid plan to lure Jose failed. After some times, the robot stopped moving and fell on the ocean's floor, since it was standing in the water and everyone began feeling happiness, but it was short-lived when they heard Jose speak through his microphone.

\- "All you Fairy Tail members out there." He began. "We have succeeded in capturing Lucy. Our first objective has been achieved."

That news shocked everyone, no one wanted to believe it, but then.

\- "AAAAAAAAAAAAHHHHHHHHHHH !" Lucy's cry was heard through the same microphone, proving that Jose was right. Sento, while feeling anger upon hearing his friend pain, was also thinking.

 _"First objective ? If capturing Lucy was a job, then what does he want ? Is it possible that their second objective is their main one ?"_

\- "We have but a single objective remaining." At that, the Phantom soldiers began changing form, looking darker and dangerous, their power skyrocketing. "To slaughter the lot of you. Disgusting brats."

Then the Phantoms rushed at the Fairies, overpowering them clearly. Sento looked at the phone on his hand and then looked up to the sky.

 _"It would be a miracle if they came right now. But miracle isn't needed, when you are as lucky as those guys."_

Indeed, a portal suddenly appear above the city and twelves lights shot out of it, landing in between the Phantom and the Fairies, surprising both side, excepted Sento.

\- "Just in time you guys." Said Sento to the newcomers.

\- "Really ? Alright, Lucky !" shout one of them.

When the dust cloud disappeared, 12 persons, some humans and other not, where standing side by side. Almost all of them were wearing a blue vest with silver design and colored design, the color different for each one of them. The guy who just talked was in the middle and was a human, at least in appearance and was wearing the red version of the vest. The other who looked like human were an orange clothed guy, with a strange tail, a sliver haired guy with a same colored vest, a girl with dark hair and green vest, a yellow clad guy with a hat, a young boy with a sky blue vest and a man who didn't wear the same vest, but a long scarlet one with a shield and sword in his hand. As for the non-human, there was a sort of wolf with blue fur and assorted vest, a golden robot who didn't wear a vest but with blue and silver painting on his chest instead, another robot, shaped like a bull, wearing a black colored vest on his right shoulder, another robot, looking like a girl with a pink vest and a purple dragon with a fancy long vest with a cane in his hand. With the exception of the scarlet guy and the dragon, they also had the same device on their wrist.

\- "So, you need help, Sento ?" asked Lucky.

\- "Yeah, i need you to help those guys " he said pointing the Fairies, "in fighting those guys." He continued, now pointing to the evil Phantoms.

\- "And the giant machine ? Do we need to use KyurenOh ?" asked the young boy.

\- "No, it's powered by magic and I don't want to take the risk of making two powers from different origin clash. Furthermore, it's not a real danger, it is not a menace anymore. So now Lucky, can I leave this to you and the others ?"

The red man, called Lucky, answered with a grin.

\- "Of course, you can." He then turned to his friend. "Let's go, guys !"

\- "Okyu ! " thet all said at the same time, taking out their Kyutama. The all put the Kyutama in their Transformation Controller, the dragon putting it in his cane and the scarlet inside his shield.

 _ **SAY THE CHANGE ! C'MON THE CHANGE !**_

\- "Star Change ! " they all said before shooting at the ground, making a star appear, while the guy with a shield drawing out a sword, the star appearing above him.

\- "Garyu Tensei !" shouted the dragon, slamming his cane on the ground.

In a flash of light, the all were clad in colorful combinaison, each with his own particularity.

"Super Star ! Shishi Red !" Lucky was now clad in a red combinaison with a star design on it and a sphere at its center. His helmet was shaped like a lion.

"Poison Star ! Sasori Orange !" Stinger was now wearing his orange combinaison, his tail clearly visible, a helmet shaped like a scorpion.

\- "Beast Star ! Ookami Blue !" Garu the wolf was wearing a fur covered armor, with a wolf theme.

\- "Trick Star ! Tenbin Gold !" The golden robot Balance was themed, funny enough, after a scale.

\- "Ring Star ! Oushi Black !" Champ the mechanical bull was the biggest, his helmet decorated with a bull head whose horns where stretching far out.

\- "Silent Star ! Hebitsukai Silver !" Naga, the silver haired man, was now clad in a silver armor.

\- "Shinobi Star ! Chameleon Green !" Hammy, the only human girl was wearing a green combination wit a chameleon shaped helmet.

\- "Speed Star ! Washi Pink !" The other girl of the group, Raptor the android, was wearing a pink armor with wings.

\- "Food Mei-Star ! Kajiki Yellow !" Spada, the yellow guy was wearing a yellow armor with a pointed helmet, like a swordfish head.

\- "Dragon Ma-Star ! Ryu Commander !" Shou Ronpo, the commander, was wearing a purple armor with a long cape.

\- "Big Star ! Koguma Skyblue !" Kotaro, the youngest member of the group, was wearing a skyblue armor with a scraf around his neck.

\- "Space Bu-Star ! Houou Soldier !" Tsurugi, the scarlet one was wearing a red armor, with a slightly different design and an earpiece on his head.

\- "The ultimate saviors ! Uchu Sentai Kyuranger !" they all posed, in front of the Fairies AND the Phantom who didn't knew what to do with them.

 _"… Why the super sentai always feel the need to do a roll call ? It was way too long, seriously. If i call a Super Sentai in the future, I better asked them to drop the roll call thing. It's neverending. Besides, I always wondered why no one attack them when they are roll calling ?"_

With that, they all drew they weapon. Seeing this snapped the Phantom and the Fairies out of their though and the fight began again. As for Sento, he was in HawkGatling and flew toward the building.

/- Later, inside the Phantom HQ -/

Sento just entered the building and unmorphed in a hallway. Not knowing where to go, he decide that the best things to do is to go up, Jose will probably be at the highest point of the build. He ran, trying to find stairs to go up. He also had to reach the place where the rockets were shot from since he had a pretty good idea about their origin. But when he finally reached a door, he heard talking on the other side and it was not something good. He opened the door slightly and what he saw didn't pleased him.

Lucy was strapped on the wall by iron shackles and Gajeel was in front of her, throwing knives at her, purposely missing, doing that just to play with her. As he was throwing a new one…

*BANG. Cling*

Sento used his Drill Crusher in gun mode, loaded with Harinezumi, to shot the knife before it could reach the wall, making his presence known to the Phantoms in the room, the Iron Dragon Slayer turning to him with a grin.

\- "Well, if it isn't one of those trash." He said, before eyeing his gun and belt. "And I've never heard about a mage like you before, meaning you are not one of their best. A trash among the trash in a way."

\- "I come from a place where, the more you underestimate your opponent, the easiest you are to beat." Said Sento casually, like he was talking about the weather. "It seems like you will be pretty easy to beat, if it's the same in this world." Gajeel glared at him, not liking what he heard, but also noticing the way Sento was talking about 'worlds'.

\- "I don't know who you are, but I must say that I've never met someone I wanted to kill so badly just after meeting him."

\- "I could say the same, but I'm not." Sento said reaching for his pocket. "I prefer knocking out instead of killing. I'm not a beast." He finished, pulling out 2 bottles. But then, he saw something against one of the wall. It was a machine, but looked oddly familiar. It had a sort of door on it and something shining lightly behind it. There was pipe coming out of it and reached all the way to the roof, going up.

\- "What is this ?"

\- "That ? I don't really know. Only Jose know how it works." Answered Gajeel, while stretching before the fight. "Some guys came a few days ago. They put that thing here with a small bottle. They also covered gave us some kind of strange substance and water barrels that the master put somewhere, saying it could help us getting rid of Fairy Tail. What was that thing called, already ? Deb…thing cell ? Wait, why am I telling you that ?"

But Sento wasn't totally listening. He was stuck on the bottle comment.

 _"I knew it. It's the Rocket Fullbottle. But how could they use a machine to use its power ? Wait, Some guys came ? Could it be… Shocker ?"_

\- "Tch, I talk too much. Now come here. Unless you are afraid." Taunt Gajeel.

\- "I'm not. But you better be ready."

 _ **GORILLA ! DIAMOND ! BEST MATCH ! ARE YOU READY ?**_ "Build Up !" _**KAGAYAKI NO DESTROYER ! GORILLAMOND ! YEAHHH !**_

He morphed in front of the shocked Phantoms and a now grinning Lucy. Gajeel quickly snapped out and rushed at him.

\- "You think you colorful armor is gonna help you win ?" Sento caugth his arm with his diamond side before sending a gorilla punch in his guts.

\- "It's not gonna help me win." Gajeel was then sent backward but managed to stay on his legs. "It's gonna help me beat you. There is a slight difference."

\- "See ? That's the power of Fairy Tail." Taunted Lucy. "You can't win."

\- "Shut up. I didn't ask for your opinion, bitch !" he then threw a knife at her. Sento was afraid, since he knew he couldn't stop it in time. But he didn't had to. Just in time, the ground between Lucy and Gajeel exploded, and Natsu came flying out of the hole, catching the knife with his teeth. When Natsu landed, he was pissed and literally covered in flame.

\- "I knew it… I recognized your smell."

 _"Did Gajeel took Lucy here because he knew Natsu would come to save her ?"_

\- "Natsu.." Lucy said tears swelling in her eyes at the sight of the flame mage, who punched Gajeel without even giving him the time to react. He then began chaining his attacks, never letting Gajeel breathe. He literally looked like, a mad beast for a moment. Sento could feel the Dragon Fullbottle in his pocket reacting.

 _"Dragon react even without being in contact with him ? How strong are his emotions right now ?"_

\- "I've never seen Natsu like that…!" said Lucy

\- "Same here.." answered Happy who pulled on the shackles to free her. Sento came to help him, helping him. _"I think I have an idea about what motivate him."_ He though looking briefly at her before turning to Natsu. The fight was still going on, Gajeel turning his arm into an iron sword hitting Natsu, before kicking him far. As they were facing each other, Gajeel covered his arm in grey scales before hitting Natsu. The fire dragon was sent back and when Gajeel tried to kick him, he literally sent up a gale. When Natsu tried to punch him, it was like it had no effect. Natsu got back and began to inhale, but

 _ **KARYU NO … / TETSURYU NO…**_

\- "That guy can use dragonbreath too !?"

 _"Shit. I wonder what kind of thing a iron dragon can breath out, but the contact with Natsu's roar is not gonna be good."_

… _ **HOKO !**_

Like Natsu, Gajeel some kind of flame, but it was a metallic grey. The two attacks collide and the breath of the explosion blew up the room. While Gajeel was protected by his scales, Natsu was hardly standing up, iron shard everywhere on his body.

\- "Even if your breath can burn your opponent to ashes, it's useless against steel." Explained Gajeel. "But my own breath of iron blades can slice up your body." But as soon as he stopped,

*CRACK*

The iron on his face cracked, surprising the iron dragon slayer.

\- "My dragon flames… can incinerat anything." Explained Natsu standing up. "If you don't come with all you have, you're just gonna get smashed to bit."

Natsu's words officialy began a war between the two. The sky was too small for two dragons, one had to be shot down. Natsu and Gajeel where fighting with so much power that each blow sent wave of wind blowing everything away. After some time, it calmed down, the two dragons panting heavily. Gajeel did something no one expected. He picked some iron from the room… and ate it. And if iron was the same for Gajeel as fire was to Natsu, it meant that…

 _"He has restored his energy."_

 _ **Tetsuryūsō: Kishin**_

He used his newfound energy to strike Natsu, who wasn't in shape to fight anymore. Natsu was being manhandled and if he wanted to win, he just need one thing : fire to eat. Lucy, remembering she still had the key she got on Galuna Island. She decided to test it.

 _ **OPEN THE GATE TO THE CENTAUR : SAGITTARIUS !**_

While Sento was expecting a centaur, a horse with a human upper body as a head, he got the opposite. A human with a horse head, but since it wasn't stupid enough, it wasn't a real horse head, but some kind of disguise, his human face sticking out. He was armed with a bow and a quiver full of arrow on his back. He stood here, saluting in a military fashion. Like Happy then said it was basically …

\- "A guy in a horse suit ?!"

\- "What the hell ?" Said Lucy surprised, but she quickly snapped out of it. "We'll go through this later but can you make fire?"

\- "Nay… I'm afraid my skill lies in archery."

"We could have guessed that. But how could we help Natsu, I have ne such thing as fire Fullbottle. But I could buy sometime. " He then ran to the machine where Rocket was supposed to be. As for Natsu, he was having a hard time. At this point, Gajeel was basically playing with him. He then launched him toward the hole in the wall, landing just at the edge. As everybody looked at the hole, what they saw made their blood run cold.

The guild was so badly damaged that it was now not strong enough to stand, and it crumbles, leaving just a pile of rubbles where it once stood.

\- "Shit, we were too engrossed in fighting those thing we forgot to protect the building. It looked important." Said Stinger, not liking that.

\- "It's not over yet." Said Shou Ronpo. "They might have lose a base, but they can still win this."

Back with Sento's group, they were so shocked no one was moving. Until Gajeel began to laugh. That's when Sento snapped. A new bottle in his hand, he rushed at Gajeel, changing while moving.

 _ **PANDA ! ROCKET ! BEST MATCH ! ARE YOU READY ?**_

Gajeel was about to strike Natsu, still on the ground with his iron sword when his swing was stopped. When he realized that, he looked down a little and saw a squatting Sento, in a new armor.

 _ **BUTTOBI MONOTONE ! ROCKETPANDA ! YEAHHH !**_

The organic Halfbody was white, with an eye in the shape of a panda head and a huge hand with big white claws that stopped the attack. The inorganic Halfbody was light blue, his eye shaped like a rocket and his arm WAS a rocket, with the thrusters on the shoulder and the head on the hand. Pushing the blade away, Sento then punched Gajeel with his rocket, the force sending him to the other side of the room. Sento then Sento another rocket punch, this one sending a rocket shaped bullet at high speed at Gajeel, who was just barely standing up. The attack sent him back again and when he stood up, he saw Sento turning the Driver lever.

 _ **READY, GO ! VORTEX FINISH !**_

White charts appeared, trapping Gajeel while Sento took off, using his rocket to fly along a line, like he was building power thanks to centrifugal force. When the power was enough, Sento stretched his clawed hand and slashed at Gajeel, the power of the strike breaking his scales. Sento then approached the iron dragon but when he got close.

 _ **TETSURYU NO HOKO !**_

Sento didn't had time to dodge and took the blow full on, at point blank range. When he finally touched the ground, he was battered up and unmorphed. When he saw Gajeel going at Natsu, his iron sword back again, he tried to get up but couldn't.

\- "The Jupiter cannon, the Elemental four … He's used too much energy ! " Shouted Happy at Gajeel, who didn't seemed to care. "If he had some fire to eat, he'd definitely beat your ass !"

"Happy's right. I might not be able to use fire, but a lot of my comrades can." Taking out his HelpPhone (A.N. : Don't judge my naming ok ?), he was about to call someone when Sagittarius voice stopped him.

\- "I see, it seems there may have been something of a misunderstanding." He said, drawing Lucy, Sento and Happy attentions while taking out his bow and an arrow, aiming right in front of him. "When you asked me if i could produce fire, I naturally said no. But it would appear that the issue here is not whether I can produce fire per se, but whether or not I could help generate it." He then shot his arrow, who flew at high speed, passing right under Gajeel nose and planting itself is some machine and almost immediately, the machine caught fire. Natsu jumped on it while other arrow were shot, making more fire appear.

\- "To set machinery aflame… is a mere child's play for my arrows…" finally said Sagittarius.

 _"He may not look like it, but he seems to be quite dangerous when needed."_

After Natsu finished eating, he punched Gajeel who tried to counter with his roar.

 _ **TETSURYU NO HOKO !**_

But Natsu did something crazy. He deflected the blow with his bare hands. As Gajeel was still trying to assimilate that, Natsu gathered his strength and launched the final strike.

 _ **METSURYU OGI : GUREN KARYUKEN**_

He unleashed a flurry of fiery punch with such a speed it looked like he had many arms. When Gajeel landed, already out of the fight, Natsu kept going, making the building break along with Gajeel's scales.

\- "Now… We're even…" Said Natsu before collapsing, not having the strength to stood up anymore.

/- Later -/

Everyone was gathered in front of the fallen building, still fighting against the specter from Phantom. Suddenly, they felt the ground shaking and a huge energy coming out of the Phantom Lord HQ. As people like Sento and Lucy asked themselves what it was, the other members of fairy Tail knew what it was and were smiling at this power.

\- "Only the old guy has this kind of power." Said Natsu, grinning.

"So Makarov is healed ? Well good for us, and judging by the energy seeping from the building, he is about to bring out his full power."

Just as Sento finished his thoughts, a huge light shone from the guild and the clouds split, as if a huge sphere was passing through them. As the light was intensifying, the specters all disappeared, one after the other.

\- "This is… Fairy Law !" Erza said, her eyes opened wide. "It's holy light cleanses those filled with evil and malice… The mage who invoke the spell can selectively choose their targets."

Once the light disappeared, the guild knew that it was over. They had beaten Phantom Lord. As everybody was happily congratulating themselves for that, something came back in Sento.

"So Shocker gave them a machine to use the power of Rocket, huh ?" Sento though, looking at the bottle in his hand. "Guess they wanted to help them since they knew I'm a member of this guild. But Gajeel talked about other things. He said water and cells ? It was Deb-something cells. Deb…oth ?"

Then, realization hit him like a ton of brick.

\- "GET AWAY FROM THE BUILDING !"

As soon as he said that, a strange green flesh-looking jelly was beginning to cover the building. Luckily, as the building was starting to stand up, the people who were still in it where ejected, Natsu landing near his friends. But as they looked up, they saw something impossible, even for their world. Where once stood the Phantom Lord HQ now stood a huge green monster, with a huge mouth full of razor like teeth, dark tentacle like hair, and fanged head as hands. The rest of the building was merged with it. Basically, it was a building who became a monster.

\- "Ok, that is not something I expected but, I think you can handle it, right ?" Sento asked, talking to Lucky.

\- "Yeah, leave it to us. Let's go guys !"

\- "Okyu !"

 _ **SAY THE GO !**_

A few seconds later, 8 voyagers came out of nowhere : a red lion, a orange scorpion, a blue wolf, a black bull, a green chameleon, a yellow swordfish, a purple dragon and a sky blue bear carrying a smaller one. As if this wasn't already too much for the mages, what came next almost killed them from shock.

 _ **SAY THE DOCKING !**_

The different ships began changing shape and combine themselves. In front of the awestruck mages, they were now altogether, forming a huge robot.

 _ **RYUTEI KYUREN-OH !**_

The lion was used as the base, the scorpion and the bear formed the arms. The null and the wolf formed the legs. The dragon was strapped to his back, with the swordfish and the chameleon on it, just above the robot shoulder. The dragon head was on the chest, surrounding the round sphere Lucky was in. As the fight began, Makarov asked a question.

\- "I need explanation about where this robot are coming from but more importantly : how the phantom base could have become such a beast ?"

\- "It's because of the Deboth's cells that was stocked inside." Simply said Sento

\- "Huh ?" was Makarov answer since what the Rider said didn't helped him at all.

\- "In our world, there was an army of monster called Debo Monsters. They were made of cell who could multiply and make them gigantic when soaked in what they called Restoration Water." Explained Tsurugi. "Apparently, Shocker gave them sample of those cells and some Restoration water. When the cells was touched by the water, the cells combined with the rest of the guild to form this thing."

As they were talking, the giant robot was fighting the beast and was little by little taking advantage. When finally, it was time to end it.

SUPER GALAXY !

The sphere on the robot began to shine, gathering energy before sending it to the dragon head in the center.

 _ **ALL-STAR SCRAMBLE BREAK !**_

Then, all the energy gathered in the head was shot, forming a colorful beam of energy, hitting the monster in the chest. After some seconds where the monster was covered in electric arc, it exploded, leaving nothing behind him.

As the robot disappeared, letting the Kyurangers gather with the others, Sento realized he'll need to explain some more things to the Fairies.

 **OK, here it is. So, I think no one expected the Kyurangers but the idea came from someone who mentioned them so I decided to use it since I had a pretty good occasion. But as I said at the beginning of the chapter, I won't use the Reinforcement thing much, and if I do, it'll probably be more for Riders than Super Sentai.**

 **Next Time : Why can he stay here ? Getting back Lucy. Spark flies at the building site. The life of the one banned by the stars and the threat of the red water.**


	16. Chapter 14 : Stay, Leave, Fight and Live

**OK, here we are, chapter 14. No big fight in it, it's more of a transition chapter. I hope you'll like it !**

 **Also, I know that some of you were surprised by the Kyurangers appearance, but I mentioned Super Sentai in previous chapter, also I teased 'Giants vs Giants', it should have been enough to give it away, but I'm also happy to be able to surprise you.**

 **The name of this chapter work like that :**

 **Stay : why Sento can stay here ?**

 **Leave : will she leave the guild for good ?**

 **Fight : do i really need to explain ?**

 **Live : Living despite his fate.**

 **It's just in case someone ask the question.**

 **I don't own Kamen Rider or Fairy Tail (or Super Sentai, since they are making an appearance here.)**

 **Chapter 14 : Staying in the spark of the stars.**

 _Italic : Sento's thoughts_

/- Magnolia. Ruins of Fairy Tail HQ -/

In front of the ruins of what was the Fairy Tail guild hall, stood three group of people, facing each other. On one side, the Fairies, led by Makarov. Everyone had been patched up, at least enough to stood with their comrades, even Levy, Jet, Droy and Reedus, the four victims of Gajeel, the painter having been beaten by the iron dragon slayer while trying to hide Lucy. On the other side, stood the Kyurangers, led by Lucky, Shou Ronpo the dragon and Tsurugi Ohtori by his sides. The third group was the Rider group, Sento being its only member.

\- "So Sento.." began Makarov. "Care to introduce us to those guys ?"

\- "Well, in my world, the Kamen Riders aren't the only one who fight for justice. There is also the Super Sentai, squadron of warrior using different kind of power to fight against evil organization. The Uchuu Sentai Kyurangers here are one of the last one who formed. Simply said, they are the protector of the universe."

\- "Nice to meet you all. I'm Lucky, Kyuranger's leader." Lucky said, introducing himself. "And here are my friends and comrades : Stinger, Garu, Balance, Champ, Naga, Hammy, Raptor, Spada, Shou Ronpo, Kotaro and Tsurugi." He introduced his friends, all greeting the mages when their name was said.

\- "Well, on behalf of our guild, I must thank you all for helping in trying to protecting our member." Said Makarov with a slight bow.

\- "It's nothing. We were called here by Sento to help, but we won't be able to stay for long. This worlds energy is, put simply, forcing us to leave." Said Stinger.

\- "If this don't let you stay, how can be able to stay here ?" asked Erza, who was standing close to Makarov.

\- "The others Riders came up with a theory." Said Shou Ronpo. "The portal was stabilized by Shocker so it could protect them from the energy of this world. They put something in the portal to make it usable, and to also protect them from being rejected."

\- "And since Sento could use it without any kind of special preparation, they think it might be linked to the nebula gas." Finished Tsurugi.

\- "The nebula gas ? it prevent me from being sucked back into our world ?" Sento said, as if he already had his doubt.

\- "Well, according to the Riders, the energy of this world act as a immune system, repelling any foreign body. It's possible that the nebula gas act, who should normally be considered as a foreign body, is letting himself get 'corrupted' by magic, so this world let you stay here." Continued Raptor. "In short, the gas let magic get to you just enough to be considered to be part of this world and let you use your power."

\- "And since I'm also partially protected from magic, it could explain why some kind of magic don't work on me." Sento completed, his hand on his chin in a thinking pose.

\- "Wait, magic have no effect on you ?" asked Gray, not understanding everything.

\- "No, magic have effect on me, but not all of it, I think some kind of magic don't work on me." Answered the physicist. "For example, when Mistgun came to the guild last time, his sleeping magic had no effect on me."

\- "Since Nebula gas seems to be the only thing able to make you stay here, the Riders are trying to find a way make the portal powerful enough to send Ryuga here." Said Stinger. "Since he was also exposed to the gas, he should be able to stay too."

As Sento nodded at that, agreeing to the idea since having Ryuga who be a great help, when suddenly, the Kyurangers began to disappear.

\- "It seems we have reached our limit." Observed Naga.

\- "Yeah, it looks like it." Agreed Lucky. "Just one more thing, Sento. We Super Sentai have some problem of our own, so don't call us unless it's something you really xcan't do without us, like a giant monster for example."

\- "He is right, but I doubt Shocker have any more ways to create giants. If that was the case, they would have already done it more than just one time." Said Tsurugi.

\- "Ok I get the message." Sento said, as the Kyurangers were now almost gone.

\- "I wish you the best in your mission and to all of you too." Said Lucky, talking to Sento then to the Fairies. "Good Luck ! "

Then, they all disappeared in sparks of light.

/- A few days later -/

It's been about a week since the Phantom Lord incident and thing didn't go as smooth as they hoped. As they began to rebuild the guild, the Rune Knights, the council's army, came to investigate about what happened with Phantom Lord. The questioning lasted all week and the fairies will have to wait for the council to decide on what to do. But as for what was happening right now,…

\- "It's heeaaavy ! " Natsu complained, while carrying a dozen wooden beam on his back.

\- "It's because you are trying to old so many at once, stupid." Said Gray, before turning his head to the other side, feeling like he was observed.

\- "HA ! That's probably your limit since you're so weak." Taunted Natsu, and it worked since a few second later, Gray had twice as much wooden beam as Natsu on his back, clearly straining to stay on his two leg.

*clap clap clap*

As he heard clapping near him, Gray look in the noise direction, seeing nothing. But it made him lose his concentration, and he soon was crushed by all the beam, Natsu laughing like a kid at his rival expense.

 _"I can't believe he is the same guy that beat Gajeel just a week ago."_ Sento though looking at Natsu, carrying tools. _"I really can't decide what to think of him."_

\- "Hey you guys." The aforementioned guys looked at the voice, seeing Erza, carrying a beam on her shoulder, dressed in builder's clothes that she ex-quiped. Sento took note that Erza seems to have an ex-quip for all kind of situation, battle or not. "If you've got time to play around, hurry up and help ! We've got to fix the guild as soon as possible."

Everyone in the guild was already giving everything they had to fix the building. Even Makarov, who used his magic to reach a gigantic size, putting the beams together.

\- "Director, where do you want this wood block to go ?" asked Erza, acting as if she really was a builder.

 _"She's really into it. Wait… Different kind of clothes, changing personality according to what she wear… So she is a… roleplayer ?"_

\- " *Rumble* I'm hungry!" whined Natsu, falling on the ground.

\- "Yeah, i'm starting to get hungry too." Admitted Gray, and as soon as he said that, someone, probably a girl judging by her silhouette, dashed in front of the boys, dropping a lunchbox in gray's hand. The lunchbox was packed with food and a little heart on it.

 _"I don't know who she is but I do know why she did that."_ When Sento saw Gray handing the box to Natsu, since he couldn't eat that much. _"And you just broke a young girl heart, Gray. Shame on you."_

Suddenly, as Natsu was stuffing his face with the lunchbox content, Loke came up to them.

\- "Natsu. Could you give this back to Lucy ?" he said, the stellar mage key ring in his hand. But what surprised the group was how tired Loki was, as he was struggling to stay on his legs. But now that Loki was mentioning her, it has been a long time since they saw Lucy. They decide to go to her place, while trying to avoid Erza who were trying to make them go back to work, but just before going, Sento saw Loki's face and what was on it was the face a lot of Rider had at some point of their life : resignation, like he knew something was coming and was ready to face it.

/- Lucy's place -/

Once they reached the blonde apartment, they were surprised to find it totally empty. Lucy was nowhere to be found. Since the apartment wasn't messy, the chance that she got kidnapped was really small but when Happy, opened a small closet, as if he was hoping to find her inside, a lot of letter fall out of it. Of course, curiosity taking the best of him as always, Natsu began to read them. As the group was examining the letters, they discovered that they were all addressed to her mother, but something was off.

 _"She hasn't sent them probably because she ran away from her home. But then, why would she write those letters just to put them in a cupboard ?"_

When Sento looked up from the letters, he saw Erza, looking down at Lucy's desk, her hair hiding her face. The rider felt that she had found something and it wasn't something good.

\- "It's Lucy's note." She said, lifting a small piece of paper. " 'I'm going home' so she says."

\- "WHAAAAAAAAAAT !?" the boys and cat shouted and their shock was understandable. No one would have expected that from the blonde stellar mage. Also, she made clear that she hated her home because of her father, so why would she go back there.

\- "She's probably feeling guilty over what happen with Phantom Lord. By going home, she probably is trying to protect us from other attack of the same kind." Theorized Sento.

\- "I don't care about the reason ! We are going to bring her back !" said Natsu, already dashing through the window.

 _"I know you want her back badly Natsu, but did you had to go through the window ?"_

\- "NATSU !" shouted so the Physicist, grabbing Salamander's attention. "We don't have time to wait for a train and she's living quite far away. So…" He took out his phone and LION ans Natsu got the message, gulping heavily.

/- Near Heartfilia residence -/

Sento was driving his Machine Builder, Erza and Gray clinging to him not wanting to fall of the vehicle. Since Natsu didn't want to go on the bike despite his desire to get Lucy's back, they put him inside a cart and was towed by the bike, looking like he was about to die. The ride was quite long when they finally reached the Heartfilia residence. Getting of the bike and Nastu getting off the cart, they rushed to the residence hoping to find Lucy before she made a big mistake. When they found her, she was in some kind of cemetery, putting flower on a huge tomb. Of course, she seemed surprise to saw the group here, so far from Magnolia. Apparently, they didn't had to worry since she only came to make sure her dad knew she was leaving for good, and also to tell him that if he tried anything against Fairy Tail again, she and the whole guild will see him as an enemy. Once they were together, they quickly left the place.

\- "You went to visit your mom's grave ?" asked Natsu.

\- "Yup." simply answered Lucy. "Sorry to worry you guys."

\- "It's not your fault. We kind of jumped to conclusion." Said Sento. As they were walking, he noticed the houses along the way, scattered across the fields. "Either way, this city his huge." _"But wait. Is that a city or …"_

\- "Ah well, this is just the garden." Explained Lucy with a smile. "My family owns all the land up to those mountains." She said pointing to mountains at least 100km away. Everyone's eyes bulged out at the revelation. As Natsu and Gray began to act as if they discovered that Lucy was a princess and Erza's mind completely disconnected from reality, Sento was shocked but also could now see why she left her home : neglected by a dad who never thought of anything but work, losing her mother at a young age, she did had a difficult life, which seemed to be mandatory to be a fairy Tail member.

/- Back at Magnolia -/

A few days later, the guild reconstruction was going well and they could, at last, go on jobs again. While everyone everyone was gathering in front of the request board, Sento, who was actually helping by re-creating a blueprint for the guild, with realistic proportions and values, since the old one, made by the master, looked like it was drawn by a kid. Everything was going smoothly when suddenly, he was hit in the face by a flying table. When he stood up, he knew where it came from. Erza was standing up in front of Luxus.

\- "YOU DARE SAY THAT AGAIN ?!"

\- "Then I'll say it again." Said Luxus, that bastard grin on his face. "This guild doesn't need weak bastards." He said, pointing at team Shadow Gear. "I heard that you guys were beaten up by Gajeel ? Speaking of which, what are your names ? Who are you guys ?" Clearly embarrassed neither Levy, Jet or Droy answered. "You're disgrace." He then turned to Lucy, a bad look in his eyes. "Well, isn't this the princess who's the cause of all this ?" Lucy took a step back and Natsu came out of nowhere and place himself in front of her.

\- "If I succeed the guild, I'll erase all the weak shits away ! And every single one who opposes me !" he said before turning away. "I WILL BUILD THE STRONGEST GUILD ! A GUILD THAT NOBODY WILL LOOK DOWN ON. THE STRINGEST GUILD IN HISTORY !"

\- "A single man guild then."

Everyone stopped talking and turned to Sento, who talked without lifting his head from his work.

\- "What did you say ?" asked Luxus, not smiling anymore.

\- "Well with an ego like yours, you can't imagine that someone can be stronger than you and if you try to do what you just said, you'll end up all alone, since I've got the feeling that everyone here will oppose you."

Nobody talked or even breathed, feeling like world was about to crumble. No one ever talked like that to Luxus and judging by the latter face, he didn't like it.

\- "I don't see what you're talking about, it's not my ego that talk when I say I'm the best, it's a statement." Said Luxus with a smile.

\- "Again with this inflated ego. In my world, overconfident persons never succeed, they just fail. Trust me, I know what I'm talking about. Also, if you want to make the strongest guild in history, why don't you create your own guild ? If you want to make Fairy Tail great, it means that you like this guild, with all his good sides and down sides." Sento finally look up, meeting the hateful gaze of Luxus.

\- "You're lucky I have a job to do. But I'll make you regret saying this. I'll stop at nothing to reach my objectives and it's not a guy like you who'll stop me." Said Luxus, his voice full of hate, before going away.

\- "I agree." Simply stated Sento, to no one in particular. "The only thing that can stop an egocentric guy gone berserk is an noisy guy with guts."

Sento returned to his plan, as everyone resumed their activities, some working on the guild, or other like Natsu's team going on a job. But he knew that Luxus will be back, and when he'll be, it won't be a good moment.

/- About a week later -/

Sento just finished the rewriting of the blue print and decide to go on a job, since he still had a rent to pay. Looking at the board, a job request caught his eyes. The job took place in the city of Balsam, renowned for its oriental architecture. Apparently, a few days ago, a monster began to attack the inhabitants, so the job was to take care of it before any other innocent was hurt. Sento decide to take it and took his bike of and rode to Balsam.

Once he arrived, he was indeed surprised by the architecture, since it looked like the traditional houses from his world. It was making him feel a little homesick. He decide to go straight to the mayor's house to discuss about the detail of the job.

/- With the mayor -/

\- "So here's the problem." Began the mayor, an old man dressed like those old wise man from movies. "A few days ago, a beast appeared near the city and attacked the citizen, but also the tourists. The victim all talked about seeing a red form and the next second, they are struck by a stream of water, knocking them out. The citizen are calling him 'The red water beast'. The monster also attacked some places like the onsen or the market. It is starting to became dangerous and if that keep going on, we could lose all of our attractivity and it could become a ghost town." He then lift his head, looking at Sento, who had a serious expression on his face. "Will you please help us ?"

\- "Of course. You can count on me." Answered Sento with a smile. The old mayor then stood up, bowing to the Rider.

\- "Thanks you, young man. I hope you'll stop this thing. Oh, and before going, I have one last thing to tell you." His face then wore a troubled expression. "A few days before the beast began attacking, a young man from the city disappeared without leaving any trace. If by any chance, those two affair are linked, please try to find him."

\- "I'll do anything I can to help you." Answered Sento before going out. Feeling hungry, he head for the restaurant but when he arrived, he saw Loki hugging Lucy close to him. If that was enough to surprise him, since he didn't though he would find them here, and absolutely not in this position. But what said Loki shocked him even more.

\- "I … Don't have much time left."

 _"Wait what ? Is he ill ? It's clear this doesn't mean that he is late for a date. What is happening to him ?"_

When Loki pulled himself off Lucy, he laughed before explaining.

\- "You fell for it. It's a trick I use when I chase girls. It help getting some sympathy."

Of course, Lucy's reaction was to be expected. She slapped him, clearly not amused by that, before leaving without even realizing that Sento was here, the physicist not messing the look in Loki's eyes. The same eyes he had when he brought Lucy's keys back after Phantom Lord. He clearly was hiding something, but it would have to wait a little, since he had a job to do. He then heard screams and when he reached them, he saw the beast, but he recognized it in a way. It was a kind of metallic monster. He had wheels on his feet and legs, the upper was red with grey pipe like a bumper, behind it what looked like a radiator grill. On the shoulders, glass panel looking like headlights. His arms and hands were wrapped in some kind of grey fire hoses. To Sento, it was clear : this was the Shoubousha Smash.

Sento pulled out his Driver and two bottles, readying himself for the fight.

 _ **RABBIT ! TANK ! BEST MATCH ! ARE YOU READY ?**_ "Henshin !" _**HAGANE NO MOONSAULT ! RABBITTANK ! YEAHHH !**_

Now morphed, he rushed to the monster, taking him by surprise. They began to exchange blows but little by little, the Smash was surpassed Sento and punched him, sending him on the paved street. Realizing that his first form won't be enough, he took two other bottles.

 _ **GORILLA ! DIAMOND ! BEST MATCH ! ARE YOU READY ?**_ "Build Up !" _**KAGAYAKI NO DESTROYER ! GORILLAMOND ! YEAHHH !**_

When the Rider punched the beast, he though that this would be enough, but the beast almost didn't moved at all and. Before Sento could do anything else, he was repelled by high pressured water, sending him on a wall of a house. In Sento's mind, he knew he had to change since close-ranged fight was out of the question because of his hoses. He had only 2 possibility : HawkGatling or RocketPanda. Thinking he would need a good punching power, he took out the blue and white bottles.

 _ **PANDA ! ROCKET ! BEST MATCH ! ARE YOU READY ?**_ "Build Up !" _**BUTTOBI MONOTONE ! ROCKETPANDA ! YEAHHH !**_

Once clad in the blue and white armor, Sento used the Space Ride Arm to pierced through the water and finally hit the Smash, with a punch powerful enough to send the monster back a good 10 meters. Knowing he couldn't take anymore risks, he turned the lever of his Driver and charged the power for his finisher.

 _ **READY, GO ! VORTEX FINISH !**_

Sento swung his left arm, sending the rocket like a missile. The rocket got the beast and took it, wending him flying in the sky, following a doted line drawn on a white energy graph. After some time, the rocket sent the Smash to Sento, whose Giant Scrapper was covered in white energy. When the Smash was at his level, he slashed him with a boosted claws. The Smash end his race in a wall, and when the beast stood up again, it was to be covered in electricity before blowing up. When the Smash dissolve revealing the human inside, the townpeople, coming out of their hiding places, where shocked : the Smash was the young man who disappeared a few days ago. As everybody was asking him question like "What happened to you ?" or "Why did you attacked us ?", Sento came up to him.

\- "Please, can you tell us what you remember ?"

\- "Well…" began the young man, visibly lost. "I was assaulted by weird looking guys. The knocked me out and when I regained consciousness, I was in a sort of glass coffin, a mask on my face. They made me breathe some kind of gas and after that, I remember a huge pain and I became this beast. I couldn't control my own body."

Sento listened and couldn't believe his ears. It could mean only one things : Shocker was doing exactly what Faust did back in Touto, they are turning human in Smash.

 _"I have to stop them before they goes to far. If they can create Smash like those, I have to stop them before they became able to create Hazard Smash, or worse."_

A few minutes later, after meeting the mayor to explain the situation and receiving his money, he head back to Magnolia, thinking about what Shocker's objective could be and knowing it couldn't be good.

/- Magnolia, a few days later -/

Sento passed all his days thinking about Shocker and their mission here. He knew it had something to do about that Zeref and his creation but he couldn't figure out what exactly. But there is something else troubling him and he wasn't the only one. Lucy was the only one who knew something was up with Loki beside himself and he had to find out what it was before it was too late. Because that's probably what Loki didn't have anymore : time. But it's only when they reached the evening that things began to move. All the guild was stressing out : Loki had disappeared. Feeling that she might know something, Sento rushed to Lucy's. When he found her, she was running and Sento caught up with her.

\- "You know something about Loki right ?" He asked the stellar mage without stopping.

\- "Yes. I asked one of my spirit and he gave me all the information I needed. Now we have to be quick or it will be too late !" she answered. The two kept running until they reached a place hidden by the forest. A kind of cliff surrounded by waterfalls. It could be a quite romantic place if there wasn't a tomb on it. And in front of it, stood Loki, his bask to the two mages.

\- "Loki. Everyone is looking for you." Said Sento, knowing perfectly that he already knew and probably didn't give a damn about it.

\- "Is this Karen's grave ?" asked Lucy, surprising the two guys. Loki because he wondered how she could know that name and Sento because he wondered how she could know so much.

\- "Stellar spirit mage Karen Lilica, is your summoner." Sento's eyes bulged out at what Lucy said, and the fact that Loki didn't say anything proved she was right. "Stellar spirit Loki, or should I say Leo the Lion."

As Loki and Lucy talked, Sento just listened. But after earing that, when a stellar mage die, his spirits returns to their world until they got a new master, he asked a question.

\- "Wait. Why are you staying here in this world if it's dangerous for you ? I got a feeling it's not just to seduce girls. Unless… you can't return there."

\- "… That's right. I've been exiled forever. Because I'm a traitorous spirit who killed his owner." Leo said, shocking his friend, before explaining why he was banned. Karen Lilica was not the best stellar spirit mage, offering one of her spirit, Aries the Ram, to the man SHE brought to the guild. And as if that wasn't enough, she punished the poor spirit, even torturing her in a way. When Leo had enough of it, he used his own power to open his door and since his door was open, it meant that Karen couldn't call any other spirit to fight. He did that to force her to break her contracts with Aries and himself but she was stubborn and refused. In the end, she fought with someone who killed her since she couldn't use her magic because of Leo, who was punished by the king of the stellar spirit.

For Sento and Lucy, this punishment was unfair, because he didn't want to kill her and did everything just to protect the poor Aries. But as Loki finished his story, he fall to the ground, his body slowly disappearing. As Loki was ready to face his death, Lucy and Sento weren't. Lucy hugged him, trying to use her magic as a stellar spirit mage to force the closing of his door. Sento tried to think about something but couldn't, it was a completely unknown field for him. As he was racking his brain to find a solution, Lucy kept trying, Loki trying to make them leave until the moment where…

\- "IF THAT'S THE RULE IN THE SPIRIT WORLD, THEN I'LL CHANGE IT !" she shouted, talking about the rules of the spirit world, which were the cause of all this.

Suddenly, as soon as she said that, wind began to blow, the water of the falls was going upstream before forming a real wall of water. Suddenly something, or someone, appeared out of nowhere in the sky. A huge old man with a long mustache, clad in an impressive armor.

\- "THE STELLAR SPIRIT KING !" shouted Leo who couldn't believe his eyes.

\- "You mean the king, the most powerful stellar spirit ?" asked Lucy, shocked by what she was seeing.

 _"That old guy is a stellar spirit ? Well compared to the man horse and the perverted bull, that's a whole new league."_

\- "Old friend, " began the king, talking to Leo. "We who pledge oaths to humans…We who bear keys, we are forbidden from killing. Though not directly, you did cause this indirectly Leo. It is forbidden for you to return to the spirit world."

\- "Wait ! " Lucy jumped in the conversation addressing to the King. "It was all for Aries sake, so it couldn't be helped ! Can't you see this was just an unfortunate accident ?! I'm telling you, how is Loki at fault here ! I'll never accept him as anything but innocent !"

\- "That's enough Lucy !" Shouted the lion. "I don't need forgiveness ! I want to atone for my sin ! Disappearing into oblivion…is fine…"

\- "I won't let you do that ! It's not a sin !" Lucy magic skyrocket as she talked, all of her spirit appearing by her side. "Caring about your nakama's feeling is not a sin !" The presence of the spirits, all summoned at the same time, shocked Loki and Sento, even if she couldn't keep the doors open for long. After some time, where the king seemed to think, he finally talked.

\- "If you would go this far for my old friend… maybe the rule is at fault here." He said, shocking Loki, but putting a smile on Lucy and Sento's faces. "You committed a sin for your comrade Aries's sake, Leo. I'll try and save that Leo, old friend." What he said next brought tears to Leo's eyes. "For the sake of that radiant bond, I'll consider this case an exception. Leo, if you still feel the guilt in you, then become the pillar for your friend and live on." He then turned to Sento. "Since I'm here, I must have a small talk with you, warrior from another world."

\- "Huh ? What ?" Sento was shocked, and his 2 friends were confused.

\- "The ones you are trying to stop are searching for things that shouldn't be found and used, dark artefact of unfathomable power. If they did, this world, our world and even yours won't survive. You have to stopped them until it's too late."

\- "That's exactly what I intend to do." Said Sento, as the King disappeared. When he was gone, a door opened behind Leo, sucking him to the place he belong, the stellar spirit world, leaving just a golden key behind him, in Lucy's hands. For Sento, he was between 2 emotions : the joy for Loki who finally was at peace with himself and anxiety about Shocker and their plans. What the King said only confirmed his theories : they are looking for what Zeref left behind and won't stop until they find what they need.

 **Wow, my longest chapter so far. It's kind of different than what I wrote before (at least from my perspective) so I hope you liked it and I'll be back for new updates soon (maximum a week)**

 **Next Time : It's Fun Time ! or is it ? Darkness on the casino. The knight locked in her past. The ambition of the corrupted. Sucking all the power in the mysterious tower.**


	17. Chapter 15 : The two faces of Paradise

**Hello, everyone ! Ready for a new chapter of 'When science meet magic' ? We start a new arc here. I hope you'll like it. Enjoy !**

 **Chapter 15 : The two sides of paradise**

 _Italic : Sento's though_

\- "You're a stellar spirit ?! "

The question asked by Natsu basically resumed everything that happened last time. Loki, now known as Leo, stellar spirit of the Lion, was saved by Lucy, who stood up to the King of the stellar spirit himself. Now back at the guild, Loki just revealed the truth about him to everyone and it was basically a big shock.

\- "Anyway, is it okay for you to just carry on as you've been doing up until now ?" asked Gray to Leo, who was talking to Happy.

\- "I'm afraid those days are long over now that Lucy's my owner…" explained the lion. "When Lucy's in trouble, I'll gallantly show up. After all, I am her knight in shining armor. Speaking of which, let's go talk about our plans for the future." He finished, before walking away, carrying Lucy bridal style. The sight, and also Lucy's reaction, made the group laugh a little, with just one exception. Natsu was glaring at Leo, heat slowly rising and Sento could swear he heard a growl coming from the pink haired mage.

\- "You know, you could just tell Lucy you love her, it would be much more simple for everyone." Said Sento seriously, the dragon slayer turning his head to him with a red face.

\- "I'M NOT !", he shouted before calming, still as red as Erza's hair. "I don't what you are talking about, but you are wrong."

\- "How can you know I'm wrong if you don't know what I'm talking about ?" countered Sento, still with his serious expression plastered on his face.

Before he could say something else, Lucy and Leo came back, a red hand mark on the lion face, probably because Lucy really wanted to go back onto the ground. As Lucy was about to close Leo's door, he stopped her to give them something.

\- "Since I can't stay in the human world for long periods of time anymore, I've got these tickets for a resort hotel that I had planned on inviting all my girlfriends to." He explained, before continuing with a wink. "You guys have really helped me out. So I'm giving these to you. You should go and have a good time. I've already given a ticket to Erza, have fun."

With that he disappeared, and just 5 seconds later, Erza arrived, wearing flip-flop a shirt covered in flower design, a straw hat and she had a buoy around her waist. She was pulling a large cart full of luggage and beach props. She was already ready to leave.

\- "Why are you guys taking so long ?", she asked, seeing the group was still un-prepared. "If you want to hitch a ride, feel free to hop on."

 _"It's not that we aren't ready, it's just you who is excessively fast to be ready."_

But soon, everyone gathered his things and head for the beach.

/- At the resort -/

It was just a nice day : the sky was blue without any cloud, the sun was high in the sky, perfect for a day at the beach. They had as much fun as they could, swimming, riding boats pulled by some kind of fish, playing beach volley, everything was perfect, even if Sento could feel something, like someone was watching them. Turning his head, he could see a blue haired girl, behind a tree looking at them, or more precisely at one of them : Gray.

 _"Could she be the one who followed us everywhere since Phantom ? Is she some kind of stalker ?"_

When night fall, they decide to head to the hotel casino. Sento wasn't a big fan of those kind of game, but he though that it would be a good way to spend the night. As Natsu was being… well, himself at the roulette, Gray, who was observing him, was approached by the blue haired girl from before and apparently, he knew her. When Sento saw the Fairy Tail insignia around her neck.

 _"Is she from Fairy Tail ? I've never seen her before ?"_

\- "Hum, Gray ?" asked Sento, gesturing between the two. "Do you know her ?"

\- "Hum, yes in a way." He answered, still not believing she was here. "It's Juvia, a member of Phantom Lord I fought during the Phantom Lord incident." Sento was wide eyed at that.

 _"She is a Phantom Lord member ? And she is the one who stalked us… no Gray, ever since the incident ? Don't tell me she is …"_

\- "So since Phantom Lord was disbanded, you want to join Fairy Tail ?" he asked even if this was kind of a rhetoric question judging by what she had around her neck.

\- "Very much so !", she answered.

\- "You know, after the stunt you pulled…" indicated Gray. "I wouldn't mind but I wonder what the master would say…"

\- "Juvia will do anything !"

 _"She seems like she really want to get into the guild. And did she just talked in third person"_

Suddenly, a big guys came and slapped Juvia out of his way. He wore a kind of turban on his head and an iron jaw-like armor. He was buff and tall, so he was towering over the boys.

\- "Gray Fullbuster and Sento Kiryu, if I'm not mistaken ?" he asked in deep voice. "Where is Erza ?"

\- "And you are … ?" asked Sento, already reaching out for his bottles.

Suddenly, water came out of nowhere and gathered between Gray and the newcomer, taking the shape of Juvia.

 _"So that is her magic ? It look like the Liquid Wizard Ring used by Haruto when he is in Water Style or Water Dragon."_

\- "Juvia won't let you lay a finger on Gray-sama." She said, spreading her arms in a protective way. "Juvia will be your opponent."

\- "Wait. You don't have to…" Gray began but was stopped by Sento.

\- "I got the feeling she'll be fine. Let's go find Erza before it's too late."

Unfortunately, it was too late already as the guy put two of his finger on his head, like Warren, the guild's telepath.

\- "You've already found her ?" he said, talking to someone via his mind. "Oh ? Is that so… Then, mind if I tidy up things up on my end ?"

Suddenly, the whole casino was plunged into the dark, as if it was a moonless night. Before they could understand what happened, they were all knocked out when the light came back. When Sento came back to him, he was behind the bar. He looked up and saw that the mirror above him was broken, it probably meant he was thrown into it. While ha was struggling to get up, he heard a well-known voice.

\- "Gray ! How could … This can't be ! Hey wake up !"

Standing up, he saw Lucy near Gray's body, impaled on an iron pole, when his body cracked and crumbled.

\- "It's probably an ice clone." Sento explained, grabbing the stellar mage attention.

\- "Please don't worry." Said Juvia, her bodyu turning into wate'r as she was pulling herself up from the ground. "Gray-sama is in Juvia's body." As soon as she said that, Gray literally fell out of her. She protected him by hiding him in her. Sento saw Lucy's expression and realized that Juvia was one of the people who attacked the guild to get her. It probably will bring back bad memories.

\- "Not your body, but mine." Said Juvia, looking closely at Lucy with a superior look on her face.

"Why did she feel the need to rub it into her face ?"

Soon after, they heard a noise followed by a huge burst of flame. Apparently, Natsu had an encounter with someone and he seems to be pissed.

\- "That blocky bastard !" he said, anger plastered on his face. "Don't think you can get away ! AAAAAHHH ! " He then took off, probably to find the 'blocky bastard' he mentioned.

\- "Let's follow him. His nose is sharper than animals, he will find them." Sento said and they all ran after him, looking for Erza and her kidnappers.

/- Later -/

\- "Where the hell are we ?"

Gray's question was a good one, but no one could answer it since they were literally in the middle of nowhere, in the middle of the sea on a small boat. They came here because Natsu used his nose to guide him, but now that they were on a boat, he wasn't so reliable anymore.

\- "Damn it ! I can't believe they took Erza and Happy while we were unconscious. How sad is that ?" asked Gray, clearly not liking that situation.

\- "An accurate assessment…To think a mage as able as Erza would be defeated…" said Juvia, but she couldn't end her phrase, stopped by Gray who glared at her.

\- "Ain't no way she was beaten… You don't know the first thing about Erza…"

\- "Calm down Gray." Said Sento, while Juvia apologized at Gray's outburst. "It's true that Erza being beaten is hardly believable, but I've already saw guys everybody though invincible fall at one point of their life. Erza isn't invincible. Also, according to Lucy, those guys introduced themselves as old comrades of Erza and when I think about it, we don't know much about her life before the guild."

A few second of silence later, a tower appeared on the horizon.

 _"It seems like we finally found where they are. Let's go find Erza."_

/- Tower of paradise -/

The only visible way to get into the tower was a staircase, but it was full a guards, so a frontal approach wasn't a solution. While Lucy struggled to prevent Natsu from rushing in, Juvia came out of the water, after using her power to find another entrance.

\- "Juvia found another way into the tower underwater." She said, coming out of the water.

\- "Seriously ? Great job !" praised Juvia, the latter turning to look into Lucy's eyes.

\- "The one who was praised was not you? It was Juvia."

 _"Did you have to do that all the time ? You don't have to be afraid of Lucy stealing Gray, she already have a dragon in her heart."_

Since the other way was underwater, Juvia created some kind of water sphere, used like an helmet to breathe underwater. Once everyone was ready, they dove to the entrance. Once inside, they were in the tower basement, but they weren't alone. Many guards were here and it soon turned into a big brawl. Natsu punching his way through the guard, Gray using his ice while Juvia used her water magic and Lucy opening Cancer's gate, while Sento was in his RocketPanda form. Once all the guard knocked out, a door opened and they reached for the main hall of the tower. To Sento and the other, it felt strange. It looked like the opponent wanted them here. But soon, some other guards came in the room and as the group was getting ready to fight, they were all slayed by Erza.

 _"I got the feeling that she couldn't be kept locked up. But I also have the feeling that the master mind behind this knew that."_

\- "Why are you guys here ?" asked the knight, eyes wide clearly not expecting to found them here.

\- "Why ? If we let these arrogant punks walk all over us, what would that do to Fairy Tail's reputation ? " answered Natsu, smoke coming out of his nose. "I have a score to settle with that blocky guy !"

\- "Go back. You guys shouldn't be here." Was all Erza said but she wasn't angry like they expected, but sadness shone in her eyes.

\- "Happy's been taken here too. We won't leave here without him !" Natsu stated, not liking what Erza was asking us. When Erza said she didn't know where was the blue cat, Nastu rushed to find him. But as soon as the group tried to go with him, they were stopped by Erza, saying she will bring the mages and the cat and asking them to go.

\- "This is my fight. I don't want to involve you guys anymore." She said that without looking at them.

\- "Judging by the situation we are in, we are already involved so you might as well tell us what is going on." Said Sento, Erza not answering, not moving at all.

\- "Erza, What it this tower and who's Gerald ?" asked Lucy, the redhair looking down as if the blonde girl had struck a nerve. "If you don't want to tell us, that's fine… Those guys said they were former comrades, but we're your friends now ! And we'll always be here for you no matter when or what."

What the stellar mage made the redhair tremble and when she finally turn to them, tears were falling down from her left eye, a sight no one expected. She wiped the tears and finally explained.

\- "I'm sorry. This fight, no matter whether we win or lose… I'm going te be gone from the public world." This clearly surprised the group, wondering why Erza of all people would talk like that. "This is the inevitable future. So, I'll tell you all everything while I'm still here."

She then explained everything. That tower was named the 'Tower of Paradise' also known as the 'R System'. A cult worshipping black magic wanted to build a tower to use a magic that could raise the dead. Since the government wouldn't have agreed with the project, the cult captured people, using them as slaves to build the tower. Erza, Gerald and the four guys who attacked them at the casino, Simon (the big guy), Miriana (a cat girl), Shou (the guy with the card) and Wally (aka block guy), were all slaves in this tower. That's also where Erza lost her right eyes as punishment and Gerald, after saving her, was locked up in a dungeon to be punished to. When she got back to the others, the cries of her friends combined with Gerald's actual situation and their lives as slave made something snapped in her and she led a rebellion, guiding the other slaves to fight back against the cult. They fought against the cult, but when they began using magic, the revolt began to falter. Erza would have died if an old man didn't used his own body to protect her. The death of that man she grew to see as her own grand-father triggered something in her and her magic appeared for the first time. Magic now by her side, she led the rebellion once again. But when she found Gerald, he was not the same, as if he became a completely different person. He became a monster, the epitome of evil and he wanted only one thing : to resurrect Zeref. Gerald then threw her into the ocean but not without telling her that if she tried to come back, he would have to destroy the evidence that the tower ever existed, and it would mean killing everyone to.

The group was shocked by what they heard and the fact that she had this burden on her shoulder for so long. But Sento also noticed something in what she said.

 _"He's trying to bring that Zeref back to life ? I can't let that happen. If this man came back and end up encountering Shocker, it would be the end. But if Erza never intended to come back, why would they bring her here ? Something is not right, there is too much unknown in this equation."_

Just then, Shou, the card mage, came up to the group, shaking, as he just learned something bad.

\- "Those words… What do you mean by them ?" he asked before shouting his own version of the story. "8 years ago, weren't you the one who bombed the ship everyone was on and then ran off by yourself ? If Gerald hadn't discovered your betrayal we would have been blown to bits !"

 _"So that's how Gerald kept them all under his control and why they perceived Erza as a traitor. Seems like this Gerald have no limits when it comes to dark plan."_

Shou couldn't, or wouldn't, believe what they said. After all, it would mean that all he did those past 8 years would have been for nothing.

\- "If nee-san is right then everything Gerald told us was a lie ?!"

\- "That's right." Answered a new voice, belonging to Simon, the big guy who attacked Gray, Juvia and Sento at the casino.

\- "You never intended to kill us at the casino right ?" asked Sento, grinning a little.

\- "Yes. In order to fool Shou and the other I was just going to knock you out but with the ice clone, I could make your 'death' a little more realistic."

Shou, hearing that his friend also never believed Gerald, fall to his knees. He was having a breakdown, not knowing who he should believe anymore. As Erza was soothing him, Simon spoke.

\- "Now that powerful mages are gathered here, we can fight Gerald but we have to stop Natsu and Wally from fighting before that."

They began to run, hoping to find Natsu before it's too late when mouths began to appear everywhere on the walls, roof and even the ground, in a really creepy display.

\- "Welcome everybody." Said a voice through the mouths, identified as Gerald's by Simon. "All the pieces on both sides have been placed. It is about to begin. The Paradise Game."

 _"Paradise Game ? Like a survival game between mages ? I feel like I'm in Kamen Rider Chronicle."_

\- "The rules are simple. I'll use Erza as my sacrifice in a ceremony that will resurrect Zeref. That is to say, if I open the gates to paradise, then I win. If you are able to prevent this, then you are the winners. To make the game more interesting, I have three more players here. You'll have to get âst them to reach me. Thus this is a 8-on-3 battle."

 _"The odds are in our favor, but I have a feeling it won't be just a matter of who's side have the most member."_

\- "Lastly, there is a special rule in play." He began again, the idea of an extra rule making the group worry. "The magic council might attack this place using the Square Satellite. It is a destructive magic called Etherion, capable of annihilating everything. It is unknown how much time remains, but when the Etherion hits, everyone will die. There will be no winner. Hence, game over. That's it, enjoy the game."

The mouths disappeared as Gerald end his explanationand soon after Shou trapped Erza in one of his card.

\- "I won't let anyone lay a finger on nee-san. I'll kill Gerald myself." He said, anger on his face before taking off despite Simon telling him not to go on his own.

\- "Drat, I'll go after Shou. You guys found Natsu !" and then he ran after his friend, leaving the four others behind.

\- "What should we do ? Sento, do you have an idea ?" asked Lucy, turning to the physicist, the latter rubbing his chin.

\- "Hum, a magic Satellite ?", he wondered when a tuft of hair stood up. "Interesting."

\- "NOW'S NOT THE TIME FOR THAT !" she shouted, snapping him out of his curiosity induced daydream.

\- "I heard you and to be honest I don't really know, but I feel something wrong with this tower, so I'll go investigate it. He then walked away, hoping to find thing that will help him.

/- Later -/

Sento was in some kind of library, looking for something that might help him find the missing pieces of this story.

"Something feel odd with this tower. Why does a magic need some kind of special building to be build ? But before that, there is that Gerald." He said, looking at a book, before opening it to read it.

 _"When he talked about Etherion and the fact that it could kill them all, it was like he knew that it is exactly what was going to happen. How can someone who spend 8 years building this tower could let it be destroyed by Etherion without doing anything to stop it ? And can he know that the council intend to use it ? Does he have a spy there ?"_ Reading a page about the System R, he found something saying they would need a lot of magic. _"What is the exact purpose of the tower anyway ? Since they need a lot of magic, it can probably be used as a way gather magic. Maybe it's architecture have something special, after all the temple on Galuna Island was used to absorb the power of… wait ?"_ Sento's brain began working faster than never, the pieces assembling and solving the mystery that this tower was. He head to a wall and broke it, before inspecting the rubles. The stones was not exactly stone, in facvt it was like some kind of crystal disguised as stone.

 _"That's a lacryma ! Wait so that means… the tower is going to …"_

Then it dawned on him. Knowing what he need to know, he rushed to find the others. When he finally found the first one of them, Gray, he was fighting someone. It was some kind of half-owl man, with wings on his back and the exact same head as a owl. He also had 2 big rockets strapped top his back. On his head, he had some pink hair, ones Sento recognized easily. Suddenly, the owl talked.

\- "Who-whoo ! Such splendid magical ability ! I think I shall capture you as well." He then open a big mouth and air began to be sucked inside of him, Gray struggling since he was little by little pulled in as well. The way that owl was sucking air was oddly familiar to Sento, it looked like he was a..

 _"A vacuum cleaner !"_

Sento put his Driver on his waist and took out two bottles, ready to join the fight.

 _ **HARINEZUMI !**_ _ **SHOUBOUSHA ! BEST MATCH ! ARE YOU READY ?**_ "Henshin !"

Gray turned his head when he heard that, just in time see a red line heading to Fukurou. It stopped just in front of it, crouching before thrusting his right fist in the owl belly, stopping him and sending him back. That's when Gray could clearly saw what it was.

 _ **RESCUE KENZAN ! FIREHEDGEHOG ! YEAHHH !**_

This new armor was red and white. The organic white part was already known, since it was one of the first used by Sento in this world, with the hedgehog shaped eye and sea urchin like fist. The inorganic part, however, was new to him. The eye was shaped like some kind of truck with a ladder sticking out of it. The arm was pretty much normal, but there was a gray crane-looking device attached to the arm. He rushed at Fukurou to stop him before he could use that aspiration again. He punched with his spiked glove, using his red arm weapon to shot water, dousing the fire when Fukurou used Natsu's magic. Taking a few step back, he turned his lever, gathering power.

 _ **READY, GO ! VORTEX FINISH !**_

The gray crane on Sento's arm extended, straight into Fukurou's mouth before pumping him full of water. While doing that, he jumped until he was just exactly vertical to him and he dropped down, crushing the owl with the Spine Knuckle. The strength of the hit was enough to expel Natsu from the owl belly.

\- "He is all yours Gray !" shouted Sento as he stood out of the way.

Gray then prepared himself before going at Fukurou.

 _ **HYOUJIN NANARENBU !**_

He then slashed Fukurou with the ice blades that jutted out of his forearms, finishing the owl man who fell to the ground.

As Sento unmorphed, he picked up Soujiki from Fukurou's body before going to Gray and Simon.

\- "Ok, guys we have a problem. We really have to stop Gerald before…"

Suddenly, a blinding light shone upon the tower. As Gray and Simon were sure this was the end, Sento could only glare at the light as he watched, helpless.

Etherion just shot, and it hit the tower.

 **Cliffhanger, guys ! I didn't though I could write this chapter that fast to be honest. The next one will be uploaded in the week or next week-end, it will depend.**

 **Next Time : The true face of the Tower ! The knight chained up on the roof of Paradise ! The swirling king came to strike the stars ! The true power of a dragon !**


	18. Chapter 16 : Last day in Paradise

**Ok, here we are for the 16** **th** **chapter of this fanfic. I hope you'll like it.**

 **I don't own Kamen Rider or Fairy Tail**

 **Chapter 16 : The last day on Paradise**

 _Italic : Sento's though_

/- Tower of Paradise -/

Etherion just unleashed his power upon the tower. As everyone looked at the tower thinking that everyone still inside just died, it was not the case for Sento. He closed his eyes because of the blinding light but he knew that they weren't going to die. When the light subsided, they opened their eyes and what they saw surprised them. The tower was now made out of lachryma, as if the light morphed the tower.

\- "What ? What happened ?" asked Simon, not understanding why they were still alive.

\- "That's what I tried to tell you before." Said Sento. "The R System is a tower made out of lachryma. The tower absorbed all the magic unleashed by the Etherion. That's exactly what Gerald wanted since he need a huge amount of magic to bring back the dead. Even if I still don't know how he could be sure that the council was about to used it."

\- "Well, we don't have any more time to lost. We must reach the top of the tower before Gerald kill Erza." The small trio head to the top and when they reached it, Gerald was activating the R System, Erza, covered in shining chains, being absorbed by the tower. Natsu rushed to her and pulled her out of it, in the nick of time.

\- "Erza is a mage of Fairy Tail. You're not having her." He said smirking at Gerald before turning his head at Erza. "The hell you think you're playing at, huh ? We've gotta head back home and do our next jib ! How's Lucy gonna pay this month's rent otherwise ?"

 _"Does it always have to be related to Lucy with you ? And then he'll deny when someone tease him about his feeling. He should stop lying to himself."_

\- "Hum, those chains seems familiar." Sento remarked, rubbing his chin while looking at the chains restraining the redhaired.

\- "He used one of your Fullbottles. A golden one." Erza said, Sento recognizing it as the Lock Fullbottle. "You have to get out of here right now. You can't fight him… You don't know the first thing about him."

Natsu then proceed to put her back on her feet.

\- "Erza. Fact is, I don't know the first thing about you either." He began, the other not understanding what he meant. "But I can still beat you !" and suddenly, he punched her in the guts, knocking her out, under the surprised gaze of Sento, Simon and even Gerald, who talk next.

\- "You're even more outrageous than the rumors say." He said. "Are you satisfied, now that you've beaten up your nakama who couldn't even move ?"

\- "Erza… was crying." Said the salamander without turning, clenching his fists. "She was whining…her voice was shaking… I don't want to see her like that, she is meant to be powerful, brutal…" He then turned to look at Gerald, full of hate. "And I want to be the Erza I know when she wakes up from this nightmare so I'm gonna fight !"

He then ignite his fists and rushed at Gerald. He unleashed a barrage of attack on Gerald, who seem to be really overwhelmed by the dragon slayer.

 _ **KARYU NO YOKUGEKI ! KARYU NO KAGIZUME ! KARYU NO HOKO !**_

As Gerald was engulfed in flame, they thought that Natsu had dealt a fair amount of damage but the flames disappeared, Gerald looked like nothing happened.

\- "Is that the limit of your ability ?" he taunted, pulling off his vest. "To think, before I destroyed you, I had wanted to see the destructive power of a dragon slayer. But this level of magic was really nothing special."

\- "What'd you say ?!" roared Natsu rushing at the corrupted mage, not liking to be underestimated.

\- "You had the nerve to interrupt my ceremony. I'm going to crush you with my heavenly magic."

 _ **METEOR !**_

Gerald suddenly moved at a blinding speed, Natsu unable to keep an eye on him, the dragon slayer getting manhandled by Gerald. Even when he tried to use his other senses since he couldn't rely on his eyes at the moment he kept getting pummeled, Gerald getting even faster.

\- "I won't let any of your attack touch me." Said Gerald as he flew high in the sky, just above Natsu. "It's over. Time for you to have a glimpse of real destructive power."

He then unleashed huge beams of light on Natsu, knocking him down.

\- "This magic is comparable in power to an actual meteor. I'm impressed that you are still in one piece. Now, let's go back to business."

 _ **RESCUE KENZAN ! FIREHEDGEHOG ! YEAHHH !**_

Gerald jumped out just in time to dodge a fire blast coming his way, turning to The red and white warrior.

\- "I have a question for you. Are you related to Siegrein, one of the councilmen ?"

\- "I'm more than related to him. He as merely a projection of myself." Explained Gerald. "Which means I know everything the council did these past few years. Like for example what happened when Natsu tried to free Erza from the council disguised as her. Which mean that I also know of you story. Those Shocker guys seems to be interested in Zeref work. When he'll be among us again, I'm sure we'll be able to find an arrangement. They seemed to have some really interesting things."

 _"So that's how he knew for the Etherion. He used his projection to convince the council to use it."_

\- "To be honest, I'm curious about your power, and I think now is the perfect time to see what you can do." He then used Meteor to rushed at the Rider, who tried to find a solution to this speed. First he needed some time to think.

 _ **NINJYA ! COMIC ! BEST MATCH ! ARE YOU READY ?**_ "Build Up !" _**SHINOBI NO ENTERTAINER ! NINNINCOMIC ! YEAHHH !**_

Now wearing his yellow and violet armor, he took out his 4-Koma Ninpoutou and used his cloning jutsu to create clones. Using them, he tried to think of a way to counter that speed.

 _"If I could at least prevent him from moving, I could do something. Wait. I have a way ! "_

He realized that at the moment Gerald hit him, sending him into a lachryma spike. When he stood up, he pulled out two bottles to replace those he already had in his belt.

 _ **LION ! SOUJIKI ! BEST MATCH ! ARE YOU READY ?**_ "Build Up !" _**TATEGAMI CYCLONE ! LIONCLEANER ! YEAHHH !**_

That's when Natsu began to come back to his senses and saw the new armor. The organic Half-body was marigold, with a lion shaped eye, the mane stretching out and a lion encasing his forearm. The other Half-body was turquoise and themed after a vacuum cleaner. The eye was shaped like one and the arm had a vacuum cleaner on his forearm and a recipient on his shoulder, probably to store what he sucked with the weapon.

\- "You think a color swap is going to help you ?" asked Gerald. The blue haired guy then took off, going straight at Sento. They exchanged blows, Gerald hitting his target more often than Sento. Then Sento used his Long Range Cleaner, sucking air and even some of the magic seeping out of the tower. He also hobbled Gerald's movement, slowing him down, and he rushed at him, still using his vacuum cleaner, and punched him with the Gold Lio Gauntlet. The blow send him back, but Gerald managed to stand up quickly after that and used his magic to fly. Seeing that, Sento remembered the first time he used this Best Match in his world and turned the lever.

 _ **READY, GO ! VORTEX FINISH !**_

Sento point at Gerald with the Long Range Cleaner, and suck him toward himself. The aspiration was so strong that Gerald almost couldn't move. While immobilizing the blue haired mage, Sento gathered energy in his right arm and punched at Gerald, sending a huge wave of golden energy shaped like a lion head toward him. The blow sent Gerald into one of the crystal pillar, destroying it in the process. However, it wasn't enough to stop Gerald who stood up, getting out of the rubble.

\- "Not bad, but far from enough." He said grinning, gesturing to his unscathed body.

\- "I know. But it was enough to get that back." He replied, showing his hand, which contained what Gerald had and used against Erza. A small golden bottle, with some kind of keyhole design on it.

The Lock Fullbottle, as Erza suspected. The sight surprised Gerald, but he quickly recover his usual grin.

Now that the bottle wasn't on Gerald anymore, his link with it was broken and the chains around Erza disappeared as she slowly began to woke up.

\- "Tch. I can't lose any more time." Said Gerald, that grin still on his face. "The tower took too much damage, the magic is already seeping out of it. I must hurry if I want to bring Zeref back, so please die already, Kamen Rider."

He then felt something hit his boot. Looking down, he saw it was a small piece of the tower, coming probably from one of the destroyed pillars. Looking at the source, Sento and Gerald saw Natsu, still face down, throwing the pebbles at Gerald. When one of them hit the blue haired guy on the chest, Natsu began laughing lightly.

\- "Hehehe, I hit you…with my attack." He began, referring to what Gerald said earlier. "This tower is made of crystal right ? And if it were damaged, it would lose its power, huh ?"

As Natsu stood up, Sento knew what he was getting at and began laughing lightly as realization dawned on him.

\- "What is so funny ?" asked Gerald, not understanding why Sento would laugh all of a sudden.

\- "It's just that, since I'm in this world, I came to realize that Fairy Tail mages tend to destroy more than helping." When he said that, Natsu thrust his fist in the ground of the tower, breaking it. Judging by Gerald face, he now knew what was going on. "Mages of Fairy Tail are specialized in property destruction."

\- "I'm still in the mood for fighting. Never felt better in my life." Said Natsu, now grinning and already burning, ready to fight.

\- "You little punk." Gerald proclaimed, his grin gone, replaced by an expression of pure hate. "I'm going to finish you in an instant. You're going to regret getting up again."

\- "I've got confidence in my own stubbornness. Come and get me if you can." Taunted Natsu with a provocative grin. Gerald then threw magic bullet at Natsu, who dodge easily. He even caught an big energy sphere send at him with his hand, before deflecting it. As Gerald used another spell, sending Natsu flying, the latter used his _**KARYU NO KOEN**_ on the ground of the tower, digging a big crater inside it.

\- "My…tower that I spent 8 years building. You…" Gerald voice was full of hate and disbelief. "Unforgivable !" He then joined his hand above his head, air being sucked to them. As Sento looked closely, he could also see the shadows were extending toward it too.

 _"If shadows are bending, it means he is bending light, or maybe… Absorbing it ? If his magic resolve around heavenly body… it couldn't be…"_

When Sento looked at Natsu, he saw Erza standing in front of him, protecting the dragon slayer with her own body. Gerald then unleashed his magic.

 _ **TENTAI MAHOU : ALTAIRIS !**_

A huge sphere of darkness, looking like a part of the void itself, was shot toward the two mages. Sento, his reaction not fast enough, could only stare as his friend were about to be obliterated. But when the smoke disappeared, they saw someone else standing in front of them. A big guy, arms spread out, the remnant of cloth on his head, a metal plate on his jaw.

Simon just took the blow to protect Natsu and Erza.

As he fell to the ground, Erza rushed to his side.

\- "What are you doing here ? Why didn't you escape ?" she asked, hoping he would survive.

\- "Oh good…" He began, his breath shaking. "I was wondering when I would *cough* be some… help *cough*."

\- "I got it ! Don't speak anymore !" she replied, her voice cracking slightly as tear appeared in her left eye.

\- "You… were always… so gentle. I…" but he never finished his sentence. His body slumping suddenly as life left him. Simon just died in the arm of the woman he secretly loved. Erza was about to cry, Sento and Natsu were shocked, not saying a word, the latter with his back to Gerald. As for him…

\- "Pathetic ! How utterly foolish ! How's that called dying in vain !" he laughed, showing how crazy he was and also making something snap inside Sento. "The situation hasn't changed one bit ! No one can leave this tower alive !"

 _ **ROCKETPANDA ! BUTTOBI MONOTONE ! YEAHHH !**_

All of a sudden, he was punched straight in the face by an iron like fist, and the punch send him crash against the crystal's formation behind him. When Gerald look up, he saw Sento, in his white and blue match, left arm extended toward him.

\- "Never in my life I have met someone I hated so much. I can't believe a monster like you is allowed to even breathe the same air as us !" Those were pretty harsh words, especially coming from Sento, but it showed how much what Gerald has done angered him. In a way that was normally only seen when he used the Hazard Trigger, he took Gerald by the throat with his left hand and, using the rocket reactor, he then took the mage for a spin, sending him crashing into, and going through, many walls and pillars. After some times, he then let him fall on the ground, and as soon as he was up, Sento return to him, preparing a _**VORTEX FINISH**_ and when he was at his level, he slashed him with his Giant Scrapper, sending him on a wall once again. When Sento land and turned to Gerald, he also noticed Natsu. He then said to the blue haired mage :

\- "Don't think it's over, it's just the beginning."

Just then, he deafening roar echoed in the tower. Turning their head at the source, they saw Natsu, eyes full white, his flames growing with each second. In his hands were bleu crystals, with bite marks, and the other realize with stupefaction what he just did.

 _"He ate the Etherion ?"_ though Gerlad, not believing it.

Natsu then smashed the ground, sending a shockwave through the ground toward Gerald. On his knees, the dragon slayer kept eating the lachryma, now almost liquid thanks to the heat of his body. But he began coughing, the veins of his face swelling as he put his hands on his throat.

\- "What does he think he's playing at ?!" shouted Erza, not understanding why Natsu would do this. "An Etherion is composed of a number of different properties, not just fire !"

As Gerald look pleased seeing Natsu suffering, Sento then turned to Erza.

\- "You see, since my first day in this world, I came to realize that logic is not something you can use with Fairy Tail, and Natsu is worse the worse when it came to it." He said with a smirk under his helmet, as he took a bottle out. "If there is one guy in this world who can succeed what he is trying, it's him."

And he was right. At the moment he said that, Natsu roared once again, all sign of pain gone as he was covered in flames taking the shape of a dragon.

 _"What ! He actually absorbed the Etherion !? "_ though Gerald without believing it.

Soon after that, Natsu jumped at Gerald, his movement so fast it was impossible to follow him. He sent his knee in Gerald's face, before grabbing him by the throat, making him go through the ground.

\- "It's all because of you !" he roared as he was piercing through the tower using Gerald as a battering ram. "You're the one that made Erza cry !" Tears began to form in the girl eye as Natsu's voice reached them. "I made a promise. I MADE A PROMISE !" he shouted remembering what Simon asked him before. To take care of Erza.

\- "SHUT UP !" Gerald counter, activating his magic. METEOR ! "You can never match my speed !" But to his surprised, Natsu did not match his speed, he outmatched it, throwing his head like a cannonball in his belly. As Gerald was in the air, he lost it.

\- "I cannot be defeated ! I will create a land of freedom ! " he said. "Zeref called to me softly, through the pain and the fear ! He asked me if I wanted true freedom ! That's right… I'm the only one who can sense Zeref's presence ! I am the chosen one ! Together with Zeref, I will create a nation of true freedom !"

\- "Taking away people's freedom is a weird way to create a world of freedom. The only thing you'll do is create a world of chaos !" countered Sento but Gerald didn't listen.

\- "The will to change the world – that alone is enough to turn the wheels of history ! Why can you fools not understand that ?!" He shouted, using his magic to draw a huge magic circle, one that Sento and Erza recognized.

\- "Abyss break ?! Are you trying to take down the whole tower ?" shouted Erza, not believing what he was about to do.

 _"Abyss Break ? The same spell the robot mage of Phantom Lord tried to use ? Ok, it's going to far."_

\- "Natsu ! Take this !" Sento said throwing what he had in his hand at Natsu. He caught it and his eyes widened when he saw what it was. It was the Dragon Fullbottle. He looked at Sento who simply nodded. "Like in Kakureta Town. Take him down."

Meanwhile, Gerald answered Erza's question.

\- "Give me another 8 years… No this time, I'll build it in 5…" he said from behind the circle. "Zeref, Just wait a little longer." But then, his concentration broke when pain suddenly struck him. A reminder of his fight with Erza. The magic circle disappeared and Natsu then took off, the power of the Fullbottle added to his own power covering him in blue flame taking the shape of a dragon as he got closer to Gerald.

\- "You're never gonna find freedom !" he roared, as he was nearing Gerald. "There's no freedom for a guy tied down by some stupid ghost ! RELEASE YOURSELF FROM THIS ! GERAAAAAAAAAALD !"

Then, his fist was covered in navy colored flames, sending a powerful punch at Gerald, the shockwave alone powerful enough to broke the top of the tower 15 meter down. The punch was so powerful it sent Gerald into the tower, making him reach the bottom of it, breaking the whole tower in the process. Despite that, most of it stood up. But it wasn't finished yet. The power of Etherion in the tower began to wild, the tower was about to blow. As Erza took an out cold Natsu on her shoulder, with Sento they tried to leave the tower. It was already too late but Erza suddenly stopped, like she realized there might be way. Sento looked at her and knew what she was going to do.

\- "Don't tell me you're going to fuse with it to stop the explosion ? Because if that's the case, I'm sorry to tell you that it won't happen."

When Natsu woke up, she had already put one of her arm in the lachryma.

\- "Erza… What are you doing ?" he asked, not liking what he was seeing.

\- ''The Etherion is going wild. The tower will blow up unless I fuse with it to stop it." She then began to be sucked inside by the lachryma, Natsu rushing to stop her. But Erza already made her choice. As she was already halfway inside, she spoke to Natsu.

\- "I cannot live without Fairy Tail. I can't even imagine a world without my nakama." She said, looking at Natsu with a kindness no one knew she had. "That's just how much all of you mean to me. If doing this can save all of you… Then I have no regrets. This one measly body… TAKE IT !" she shouted the last part, as if she was talking to the lachryma.

And the crystal absorbed her.

/- Meanwhile -/

The other member of the group, Gray, Lucy, Happy, Juvia, Shou, Wally and Miriana watched the scene before their eyes, helpless, as the tower began to explode. But the blast looked strange. It was twisting around the tower and heading for the sky and a few minutes later, the tower was gone, leaving no trace of it behind. For the group, it also meant that they just lost their friends. As tears began to fall for the now gone comrades, something happened. Out of nowhere, Natsu appeared, Erza in the arm of the dragon slayer. Erza didn't seemed to understand how she could still be alive. Sento, who just appeared dragging a kind of sledge answered for her.

\- "When you got sucked inside the lacryma, it created a vortex of magical energy surrounding the tower. Natsu basically dived in to pull you out off it. Me on the other side, I used HawkGatling to fly away." He then smirked before carrying on. "On Galuna Island, I said to Gray that there is no such thing as 'there is no other way', there's always at least another way to solve a problem, even if it's not the easiest."

\- "We're the same." Finally said Natsu, talking about what she said about how she couldn't live without Fairy Tail. "It's the same for all of us… Don't you ever do a thing like that again…. NEVER" he ended, tears falling down as Erza put her forehead on his. As the other reached them, Sento could see they all looked relieved and happy to see them all alive. But he could see something else in Lucy's eyes as she looked at Erza and Natsu.

\- "It's just that they are in the heat of the moment, you don't have to be jealous." He said bluntly, surprising her and making her stutter.

\- "W-w-w-What are you t-t-talking about ? I'm n-not jealous !" she answered, as red as Shoubousha.

\- "Sure you aren't."

As everyone was happy to see them again, Miriana then asked THE question.

\- "Where is Simon ?"

Silence follows, and facing the lack of answer and the expression of the group, the answer came by herself. The whole group looked shocked as reality hit them like a ton of brick.

\- "No… It can't be …" asked Miriana, tears in her eyes.

\- "It is. He died protecting us from Gerald. He died as a hero." Answered Sento, looking down.

\- "But his body disappeared with the tower isn't it ? Then we won't even be able to bury him like he deserve it" cried Shou, tears falling freely from his eyes.

\- "Well… Not exactly." Sento said before pushing the sledge to them. The eyes of the group before him widen, guessing it was what they though it was. Sento pulled the cloth off, revealing Simon's body. "I just couldn't let him disappear like that. He deserved a better end."

Erza and her old comrades throw themselves at Sento, thanking him while soaking his clothes with their tears. When they got off of him, they were all still crying, but there was more tears of joy now, happy that it was all over, Natsu with his arm around Lucy's shoulder, Juvia standing next to Gray. It was now time for them to go back, but Sento, as he looked at where the tower once stood, couldn't shake off the feeling that it was not the last time they heard about Zeref.

 **OK Here we are. I hope you liked it. Stay tuned for the next chapter.**

 **Next Time : Let's fight for Fairy Tail ! Unlocking the fantasy to calm a devil ! A temporary squad to wreck the hall ! Waking up in the cathedral.**


	19. Chapter 17 : Fairy Tail's battle

**Ok, here we are, ready for chapter 17. I hope you'll like it. Enjoy !**

 **I don't own Kamen Rider or Fairy Tail.**

 **Chapter 17 : Fight for Fairy Tail ! A match, a squad, a dragon.**

 _Italic : Sento's though_

/- Magnolia -/

Sento was actually in his basement, looking at his equations one last time. As he was gathering his things before heading to the guild, he thought about what happened a little more than a week ago at the Tower of Paradise. After destroying the tower, they head back to the hotel. The first thing they did was to bury Simon. They even held a small ceremony, since he clearly deserved it. As no one knew what to do in those situation and even though it was not his world and that the customs weren't the same, Sento directed the ceremony, since he was the only one who knew what to do (the minimum at least). Once it was done, Erza said goodbye to her three others old comrades, who decided to explore the world, embracing their newfound freedom. But globally, everything was alright. They got back to the guild and everything was back as it was before. As Sento was ready to go, he was in a good mood and had a good reason to be. He got a call from his world that they find a way to kept the portal open, for a small amount of time yes, but it meant that he will soon have someone to work with and it put him in a great mood. He then got in the street and head for the guild. But while he was on his way, he heard people talking.

\- "You know what exactly is happening in the city right now ?"

\- "No. I just know that those mages are running everywhere, as if looking for something."

\- "I swear. I saw them fight each other all of a sudden."

Those kind of talk wasn't strange, after all the guild was known to be doing things that leave the citizen of Magnolia puzzled. But it was strange to Sento because if brawl in Fairy Tail was a common occurrence, they never did it outside the guild. Sento quicken his pace, hoping to get answer at the HQ. When he got to the newly restored guild hall, still as impressive as usual, he could see that something was up. He knew the guild had some kind of Miss Fairy Tail Election, which was why he was at home, since he find it kind of stupid, but no one was here and on stage, he saw statues. To be more precise, statues looking like the girls of the guild, he saw Lucy, Erza, Mirajane, Levy, Juvia, Bisca, Kana and all the other girl and he got the feeling that those weren't just statues but the girls themselves. Looking to hearing some shouting, he saw Makarov with Gajeel and Natsu. Makarov was shouting something about not believing there was just those two left.

\- "Hum… Excuse me ?" he said, clearing his throat. The three mages and flying cat looked at him and, a few second later, throw themselves at him, who stood still not understanding what was happening.

\- "SENTO ! SO YOU WERE THE LAST ONE ?", shouted Makarov, looking like he was about to cry. "YOU HAVE TO GO FIGTH HIM AND FREE THE GIRLS !"

\- "TIME OUT !" shouted the physicist, instantly calming them. "If you could explain what his happening, that would be nice."

\- "Luxus is back." Began Makarov. "And he is with his personal bodyguards. The Raijinshu."

\- "Who ?"

\- "They member of Fairy Tail too." Continued the master, answering the Rider's question. "They changed the girls into stone and forced us to tale part of what he call 'the War for Fairy Tail'. The objective is to find them and beat them before the girls turn to sand. But the city is covered in runes used by Luxus to trap our friends and make them fight each other's. From here, we can see what happened thanks to those runes." He finished, gesturing to the runes on the entrance of the guild. Sure enough, there was words forming in the air, writing things like 'Remaining contestants : 4' or 'Bickslow vs Gray, winner : Bickslow'.

\- "I knew Luxus could be a sadist, but this is way worse than what I though." He said, looking at the runes. "And why are you still here ? Why aren't you fighting ?"

\- "There are runes around the guild saying that statues and people older than 80 can't get out." He said, Sento realizing that those runes probably created zones with their own rules. But he then realized something. "Wait. Then, why are YOU still here ?" He said, now pointing at Natsu and Gajeel.

\- "That's the problem. They can't go out of there." Makarov said, and Sento frowned. How could they be trapped here if they weren't statues or old man ? Or are they ?

\- "You are the only one who can go out there and fight Sento. You need to find and beat at least Evergreen, the only girl of the Raijinshu. She's the one who petrified the girl."

\- "It's going to be complicated. All alone against all that, I can't do it."

Then, Natsu head to the girls, and when they asked him what he was about to do, he answered :

\- "I'm going to revive Erza. She can take care of those guys."

\- "W…Wait a moment ! How do you mean to… ?!" asked Makarov, probably already knowing that he had a bad idea.

-"If I burn it, it'll come off, right ? The stone or whatever." He said, completely serious. "Well, Won't know until I try !"

\- "AAAAAAAAAAAAGHHH ! Oh yes, we do ! Stop ! Are you trying to kill her ?" shouted the master, trying to stop Natsu while Sento looked at them doing, not knowing what to think of it. Suddenly, a crack appeared on Erza's face, to the horror of the boys.

\- "Oh crap ! I cracked her ! Glue, I need glue ! Happy ! " shouted the fire dragon slayer, while the flying cat head to find glue.

\- "You idiot ! You think that'll fix it ?! …" said Gajeel.

 _"Well at least stupidity isn't a characteristic of all dragon slayer. Gajeel can actually use his brain."_

\- "… Obviously you have to melt my iron down with your fire and we'll weld it !" finished the iron dragon, pulling out his arm now made of metal.

 _"… Is there at least one normal dragon slayer out there ?"_

The crack then expanded, causing Natsu to begin praying, begging for forgiveness to whatever god he believed in when suddenly, the stone vanished, freeing the knight, much to the shock of the guys in the room.

\- "I feel hot… Was that you Natsu ?" she asked, a dark aura around her. "What the hell were you playing at ?!" she asked, sending the two dragon slayer flying with one swing of her arm.

\- "Erza, but how … ?" began the master when Erza answered.

\- "I don't really know myself… Perhaps it has something to do with my right eye…" she said and Makarov expression shown that it was that.

\- "What is the connection with her eye ?" asked Sento, not understanding.

\- "The Raijinshu all possess secondary abilities within their eyes. Evergreen can turn into stone people looking at her eyes."

 _"That explain why it doesn't work completely on Erza since her right eye is not a real one and why the girl were petrified without fighting, they weren't expecting it."_

As Erza was now back, the number of contestant got back to 5, but quickly turned to 6.

\- "6 ? But everyone is still petrified. Who could that be ?" asked Gajeel, Erza answering with a smile.

\- "It looks like that man has decided to take part in this battle…"

Indeed, Mistgun was back at Magnolia and Erza rushed to the city, trying to find Evergreen to break the spell and free the other girl. But just then, a chime could be heard and looking at the runes, they saw that the number of contestants dropped to 5.

\- "They probably got Reedus. We asked him to go find Porlyusica, since she might now of a way to free the girl." Explained Happy but everybody was confused, and shocked in Sento's case, when they saw what was also written on the runes.

'Reedus vs Shocker Squad. Winner : Bugster'

 _"Bugster ? Don't tell me they are also there ? But if they are on those runes, it might mean that they are working with Luxus ? What are you planning, you idiot."_

\- "What is a Bugster ?" asked Happy turning to Sento, since he looked like he just saw a ghost.

\- "I already told you that in my world, there are many Kamen Rider, each one have fought a different kind of monster. The Bugsters were the one my predecessor fought. It seems like Shocker have more help than I thought." He said before thinking about that _. "And it say 'Shocker Squad'. It mean that there isn't just one Bugster but many. There is also the chance that there is other kind of monster. I need help."_ He though, taking out his Reinforcement Phone, launching many application at once _. "Let's hope they'll come fast enough."_

As Sento was there, he also thought about why Gajeel and Natsu were stuck here.

 _"One thing is sure : they aren't statues. So it's the second statement that work on them, no one older than 80 can get out. But they clearly aren't, or at least in appearance. Is it because they are dragon slayer ? Or maybe, they time traveled. If they came from the past, it could explain it : looking young but being 80 years old. But Natsu was in this guild since Igneel disappeared, a kid can't time travel by himself. Unless…"_

He didn't had time to finish what he was thinking about because new runes appeared and for once, it was good news.

'Erza vs Evergreen. Winner : Erza'

As soon as he finish reading this, the girls were all freed from the stone and it meant two things : first, Luxus just lost his hostages and two, they was now a lot more people to fight against him. When Natsu saw that, he nearly tackled Lucy, happy to see her free again. But when he saw the looks the others were throwing him, he quickly took a step back, face red as he returned to his old self, but his little scene was now written in the memory of everyone, especially in the brain of a white haired matchmaker. But the happiness was short lived. Soon, screen appeared everywhere in the guild hall and Luxus addressed the group.

\- "It's seems like we lost one of our rules. So I'm going to make a new one." He said, no one liking where this was going. "So has to keep this battle of Fairy Tail moving, I've activated the Hall of Thunder."

\- "The Hall of Thunder ?!" repeated the master, wide eyed. Apparently, this wasn't good for them.

\- "Only one hour and ten minutes remain… Do you think you can defeat us ? Or will you play nice and retire ? 'Master' AHAHAHAH ! " With that, the screens disappeared and Makarov began shouting.

\- "What on earth are you thinking Luxus ?! Are you trying to drag innocent civilians into this ?! "

 _"Innocent civilians ? What is this hall of thunder ?"_

But then, the master placed his hand on his heart, his face bend by pain before falling on the ground, struggling. As people began gathering around him, Mirajane came from upstairs, asking the ground to go outside. Once outside, they saw a lot of thunder lachryma all around the town, floating in the sky. As Kana explained, if those lachryma were to unleash their power, the entire would be destroyed. And as if it wasn't enough, when Bisca tried to shot down one of those lachryma, she was knocked out, as if struck by lightning. Those lachryma were protected by a magic which send back all the damage done to it.

 _"Luxus is really ready to destroy the city just to reach his goal ? He really got no limit."_

As for Sento, he couldn't stay without doing anything and rushed outside with the other girls.

/- Later -/

Sento was still looking for that Shocker Squad, running through the city. He was about to use his HawkGatling to look from the sky when suddenly, he felt a huge power somewhere in the city. He could see the cloud disperse showing that the owner had a tremendous power but Sento could feel that it was an evil one. Thinking that might be Shocker, Sento ran toward it. When he reach the place, he was shocked by many things : Elfman, Juvia and Kana knocked out and two demons fighting : one with green hair and a female one who caught his eye. Those eyes and white hair, he recognized her immediately : Mirajane.

 _"Well, talk about a hidden power. But she seems to be lost in madness."_

Indeed, she looked like a beast. She was trashing the other demon. When the said demon finally touched the ground, it was reveal to be one of the Raijinshu, Freed. But Mirajane didn't seemed satisfied and was about to kill him. Sento couldn't let her do it, knowing it be hard for her to live with it. Killing someone against his own will was something he know too well and it's something no one should live. He took two bottles out and rushed at the she-demon.

 _ **HAGANE NO MOONSAULT ! RABBITTANK ! YEAHHH !**_

He tackled the girl, pushing her off the green haired guy. The demon's attention shift to the Rider and jumped on him and despite his agility, he took many blows from the demon. Realizing she was in a completely different league, he knew he had to take out his most unstable weapon. He draw out two bottles and took a deep breath.

 _ **DRAGON ! LOCK ! BEST MATCH ! ARE YOU READY ?**_

This announcement didn't stopped Mirajane, but she frowned when she heard the bottles name.

"Build Up !"

 _ **FUIN NO FANTASY STAR ! KEYDRAGON ! YEAHHH !**_

Sento was now clad in a new navy and gold armor. The dragon half had an eye shaped like a dragon head and white spikes on his arm like a dragon spine. The lock half eye was whaped like a lock and on his arm, he had a key like blade on his wrist while his shoulder was a lock, chained to the key. Sento was ready to fight when suddenly.

\- "KYYYYYYYYYYAAAAAAAA !"

Mirajane suddenly squealed, coming back to her human form and fell to her knees, mumbling to herself.

\- "He did said a best match is a combination of bottle with the best compatibility. It's a dragon and a key. Like Natsu and Lucy ! It's a sign ! They are a match made in heaven ! I KNEW IT !"

Sento stared at her, not knowing what to do. If he knew that one day, he could use his best match like that, he would have laughed. He was about to unmorph when he was suddenly shot by something. Turning his head, he was now facing the Shocker Squad, but it wasn't what he expected.

The one who just shot him was a Smash. It was blue with a head shaped like a skull. His shoulders put together formed some kind of boat with cannon pointing at Sento. One of his hands was shaped like a hook, and his other like a cutlass. But it was who he was with that truly surprised him. He knew there was a Bugster since it fought and beat Reedus but this was Salty Bugster, the first Bugster Emu fought as Kamen rider Ex-Aid. It was blue with a top hat and a cape. His right arm was pretty normal while the left one was some kind of snail shaped gauntlet whose 'eyes' could release electrical bursts. But looking at the other, he realised he did a good thing calling them to help. The first one was Magma Dopant, a demon-like beast seemingly made of magma, with black legs and arms and fire coming out of his body, mainly from the neck and back. Next to him was a Yummy, the Kamakiri one, like a giant praying mantis, with the blades on his hands and small red sphere scattered on his torso. The next one was a big red armored guy with blue sphere on him. He was carrying a big club like weapon. The Orion Zodiarts. Then was a Phantom, the Minotaurus, white and blue with big horns and an halberd in his hands. Next came the Byakko Inves, the bottom half white and the upper half green, a reptilian like face and a huge clawed right hand. Next was a big monster, violet veins covering his body, his wrist connected to some kind of pointed boosters. A Roidmude and to complete the roster, a Gamma, the Katana Gamma. Dressed with a white vest with blue touches, armed with a big sword. Those were the first monster fought by the different Riders of the Neo-Heisei era.

\- "What the hell are those things ?" asked Mirajane, who snapped out of her matchmaker mode.

\- "Those are the different kind of beasts the different Riders fought through their life." He explained. "Fighting them all is going to be hard. But I kind of prepared myself when I saw that Reedus was beaten by a 'Shocker Squad'." As soon as he said that, a portal open just above them and 9 objects came out of it. When the smoke from their landing was gone, 9 men were gathered beside the group of mages. They were the Neo-Heisei Riders, from W to Ex-Aid, all gathered to help Build.

\- "Well. It seems like you have a good reason to bring us all here, isn't it ?" said Shotaro, a hand on his fedora.

\- "Yeah and probably for more than those guys but we have not much time, so is it ok with you if we keep the questions for later ?" asked Sento, remembering that after those monsters, they had to take care of the Hall of Thunder.

\- "Ok if you say so. Even if I got the feeling that we won't stay long enough to get those answers. Anyway, let's get to it !" remarked Kouta before bringing out his Lockseed, the others doing the same with their own trinkets.

Shotaro and Philip took out their Gaia Memory. _**CYCLONE ! JOKER !**_

Eiji took his three main medal and put them in the Driver, before scanning them.

Haruto put his right hand on his driver, triggering the transformation standby by announcement before putting his Flame Ring on his left hand. _**SHABADOOBI TOUCH HENSHIN !**_

Kouta opened his Orange Lockseed, the Orange Arms appearing out of nowhere by opening a hole in the sky with zipper. _**LOCK ON !**_

Shinnosuke turned a switch on his Driver before pulling out a small red car and sliding it in the Shift Brace. _**START YOUR ENGINE !**_

Takeru took out his Ore Eyecon, pressing the button on the side before putting it in the Ghost Driver, closing it to free the Parka Ghost. _**EYE ! BATCHIRIMINA !**_

Emu put his Driver on before pulling out his Gashat, pressing the button. _**MIGHTY ACTION X !**_

Gentaro put his Driver on and pressed on the for red switches on the front before taking his stance. _**3! 2! 1!**_

"HENSHIN !" They all shouted at the same time.

 _ **CYCLONE, JOKER !**_ / _**TAKA, TORA, BATTA : TA-TO-BA ! TATOBA, TA-TO-BA ! /**_ _**FLAME, PLEASE : HI-HI, HI-HI-HI ! / SOIYA ! ORANGE ARM : HANAMICHI ON ST AGE ! / DRIVE : TYPE SPEED ! / KAIGAN : ORE ! LET'S GO ! KAUKGO ! GHO-GHO-GHO-GHOST ! / GACHAN ! LEVEL UP ! MIGHTY JUMP ! MIGHTY KICK ! MIGHTY MIGHTY ACTION X !**_

Mirajane was surprised by what she saw and didn't know where to look when they all rushed at the Shocker monsters. There was action everywhere and she couldn't keep her eyes on one for long. She could at least see that the Riders were clearly dominating. After a short moment, they all lined up, the shockers monsters in front of them, lined up too, but struggling to get up.

JOKER MAXIMUM DRIVE ! / SCANNING CHARGE ! / ROCKET, DRILL LIMIT BREAK ! / CHOINE, KICK STRIKE ! SAIKO ! / ORANGE SQUASH ! / HISSATSU ! FULL THROTTLE : SPEED ! / DAI KAIGAN : ORE OMEGA DRIVE ! / KIMEWAZA ! MIGHTY CRITICAL STRIKE !

They all then jumped, destroying their respective enemy with a kick strike while Sento was about to finish his with the KeyDragon finisher.

 _ **READY, GO ! VORTEX FINISH !**_

He used his Bind Master Key to throw chains at the Smash, restraining him. While he was locked, Sento gathered a blue fire on his left hand and throw a big blue fireball at it, blowing him up. As soon as he finished, he fell to his knees, the use of KeyDragon already taking it's toll on him, which made him power down, like the other Riders. He stood up, with difficulties, before going to the poor guy who was the Smash. He took the Kaizoku Fullbottle before asking him what happened to him and his answer was the same as the guy who was transformed into the Shoubousha Smash back in Balsam. But he add something that caught his attention.

\- "While I had no control of my body, I remember the other talking to a guy with a lightning shaped scar." Began the young man, getting the attention of Sento, but also Mirajane who recognized the scar as the one Luxus got. "They said that they would give him an army to help him make his guild the most powerful ever. He agreed but it was a plan within a plan, since this army who be loyal to Shocker."

\- "And they could use this army to control the city via Fairy Tail." Finished Sento. "It looked like the kind of backstab they would do. And I got a feeling that Luxus is too lost in his anger to see the truth."

\- "Hey everyone, can you hear me ?!" Sento look around him to see who was talking to him but he saw no one, and when he saw that Mirajane heard it too, he understood. It was Warren, who was talking to everyone telepathically. "We have to take out those floating things in the sky or the city is toast."

Normally, everyone would have listened but they were to busy screaming at each other over things like 'why did you attacked me ?' or 'Why did you used this on me ?' but it was short-lived when they agreed in taking care of the lachryma before anything else. But someone asked a question.

\- "I don't think were are enough to take care of all those things." It was Erza and she seemed tense. "I can take care of about a third of them, but we aren't enough to destroy them all at the same time."

\- "Don't worry about that, Erza." Sento said, trying to be reassuring. "I have some help, we can do it."

He then turned to the other Riders, explaining the situation to them. They then all changed form, according to what they needed. W in LunaTrigger, OOO in Tatoba, Fourze in Fire State, Wizard cloning himself 4 times and taking out his WizarSwordGun in Gun mode, Gaim in his Jimber Lemon Arms, Drive in his Formula Type with his Trailer Hou, Ghost with Robin Hood Damashi and Ex-Aid in Mighty Brother XX with the Gashacon Key Slasher in gun mode. Sento took his HawkGatling Best Match and they shot in time with the others mages and a few seconds later, the Hall of Thunder was destroyed. Sento, still morphed turned to the other remembering something.

\- "Hey guys, I forgot something." He began, the thoer looking at him, tilting their heads. "When those things are destroyed, it send back all the damage it takes."

\- "He ?" was all they could say before they were shocked by the lachryma backfire.

\- "YOU COULD HAVE SAID THAT EARLIER !" Shouted Shotaro, now unmorphed trying to go punch Sento, being held back by Gentaro.

\- "Well, it doesn't matter. I still have to stop Luxus." Said Sento, as if Shotaro didn't exist.

\- "You sure you can do it ? You just used KeyDragon and got thundered by those things." Asked Shinnosuke, before Eiji came in to add something.

\- "Well, he won't be alone for long now, isn't it ?"

\- "Oh yeah. I forgot he was here. When he'll got here, can you send him to the cathedral, Mirajane ?" Sento asked the barmaid. "I'm sure you'll know him when he'll get here."

With that, he took off to the cathedral.

/- At The Cathedral -/

 _ **RAIRYU NO HOKO !**_

The thunder roar destroyed half the cathedral hall, but when the smoke cleared, Luxus discovered that neither Natsu nor Gajeel was killed. They were on the side, with a red and blue armored guy next to them, who then rushed to him almost immediately.

\- "You ! I wanted to take care of you myself." Smirked Luxus. "At least i won't have to come get you."

\- "Is that why you hired Shocker to take care of me ?" replied Sento, triggering Luxus.

\- "You little…" they began to exchange blows, but no matter what Best Match he used, because of his fight with Shocker, using KeyDragon and being struck by lightning, he wasn't at his best and was sent back to the ground, next to the other slayers. Suddenly, Luxus began gathering his energy, trying to use Fairy Law.

 _"Can he do it ? I mean, he IS Makarov grand-son, put he really know that spell ?"_

As he was gathering his energy, Levy entered the cathedral.

\- "Stop Luxus !" she said, trying to get Luxus's attention. "Your own grandfather…is on Death's door !"

This made everyone go wide eyes, even Luxus, but his reaction was not what it should have been.

\- "Well that suits me just great ! Looks like my chances of becoming master just went up again !" he said, smirking like the monster he became.

"This guy. Is he still human ? No way a sane person could say this without second though."

Then, Luxus did it. He unleashed Fairy Law, the holy light covering the whole city. When light subdued, Luxus was shocked to see that no one died, as if it didn't worked.

\- "Impossible !" he roared, not understanding why it failed. "How can anyone survived an attack of that magnitude ?!"

\- "It's your heart Luxus." The answer came from freed, leaning against the cathedral doorframe. "Your power and magical abilities aren't the only things you've inherited from the master. You also got a heart that care for its comrades."

 _"He is right. Fairy Law work only on the ones the caster see as his enemies. Which means that deep down, he care for everyone at the guild."_

\- "No ! Anybody who get in my way is an enemy !" he shouted, losing it completely. "I don't care what the hell happens to this old fart ! I AM MYSELF ! I'M NOT HIS GRANDSON ! I'M LUXUUUUUS !"

 _"So that's why he is like that. Because he want to be seen for what he is and not for his family. It's understandable."_

\- "What the fuck you are saying ?" a voice said before a small flying object rushed at Luxus, shooting at him with small blue fireball. The thing was in fact a small blue dragon, flying back to where he came. He was now flying around a young man, wearing black pants, a blue and white vest on a black shirt and another shirt tied around his waist.

\- "You took your time, you idiot."

\- "Is that a way to welcome me, you dumbass."

\- "Who the hell are you ?"asked Luxus, eyeing the newcomer.

\- "You don't need to know." Simply answered Ryuga.

\- "Hey ! Catch that !" shouted Sento, throwing the Dragon Fullbottle at him. "I think you'll need it."

With a smile, he grabbed it while the small dragon land on his hand, folding himself into a square shape. Ryuga then shook the bottle and plugged it inside the dragon. He then took out a Build Driver, much to the surprise of the mages and plug the dragon inside it.

 _ **WAKE UP ! CROSS-Z DRAGON ! ARE YOU READY ?**_

Like Sento, he turned the lever, the Snap Ride Builder appeared, but the two Half-body were the same, navy colored with dragon shaped eyes.

"Henshin !"

The two Half-body closed on him, now clad in a Build like armor but dragon-shaped energy flew at him from behind, wrapping around him, putting some orange flame design on his armor.

 _ **WAKE UP BURNING !**_ _ **GET CROSS-Z DRAGON ! YEAHHH !**_

\- "I'm not gonna lose !". Right after he said that, he rushed at Luxus and the fight began. They exchanged blows, apparently on par, much to the surprise of the other mages in the cathedral. They kept going for a good moment, before Ryuga took a few step back, taking advantage of a small moment of inattention from Luxus and he began turning the lever on his Driver.

 _ **READY, GO ! DRACONIC FINISH !**_

Ryuga then summons a blue and orange energy Chinese dragon that flies behind him, then jumps up as the dragon breaths fire, sending him at Luxus, then delivers a roundhouse kick whilst his foot is covered in blue energy. The strength of the kick sent Luxus back in the cathedral rubbles but he was still good to fight. It was at this moment that Natsu got up despite his wounds.

\- "So what if you're the old man's grandkid ? Does that make you so special ?" he asked Luxus, who turned his head to look at him. "Don't you get hung up over some stupid blood relation ! The guild is the only family we need ! "

\- "How could you understand ?" asked Luxus, anger boiling again inside him.

\- "Do we have to understand you to be your comrades ?" answered the fire mage, igniting his fist. "We reach our hands out to one another to get past that ! Luxus !"

\- "SHUT UP ! NATSU !"

With that, they began fighting again, exchanging blows with more energy than before. But Luxus had the upper hand, sending Natsu to the ground with each blows, but the young man kept coming back to his feet, his resistance shocking everyone, even the Riders and thunder mage.

\- "You stupid kid, I'll burn you so bad there won't be ashes left of you !" he shouted, creating a spear like weapon made of lighting.

\- "Luxus stop ! If you use that magic on Natsu now…" Freed didn't have time to finish his sentence when Luxus unleashed his power.

 _ **RAIRYU HOUTENGEKI !**_

Luxus then throw a three pronged spear made of thunder at the fire dragon slayer, despite the runes mage protestation.

\- "Are you trying to kill him ?!"

Natsu, too weak to move, was about to get struck. Ryuga was ready to jump in when suddenly, the spear took a 90 degrees turn, heading right at Gajeel, whose arm was changed into an iron pole, taking the full attack in Natsu's place.

 _"Did he just used himself as a lightning rod ? Just to protect Natsu ?"_

\- "Go !" was all Gajeel said at Natsu before falling to the ground. Natsu, with a new strength, stood up again and struck Luxus with everything he got, chaining his attack without stopping.

 _ **KARYU NO TEKKEN ! KAGIZUME !**_ _ **YOKUGEKI ! KENKAKU ! SAIGA !**_

Those attacks were strong enough to really hurt Luxus, much to the shock of everyone.

\- "This magic… It smashes through dragon scales…crushes dragon entrails…reaps dragon souls…" said Levy, like she was repeating what she had read in a book, which was probably the case.

\- "The ultimate dragon slayer technique …" completed Freed, before Natsu unleashed a torrent of crimson flames at Luxus.

 _ **METSURYU OUGI : GUREN BAKUENJIN !**_

Luxus was sent flying by the strength of the attack and when he fall to the ground, he was unconscious. Natsu had done it. He defeated Luxus, putting an end to the Battle of Fairy Tail.

/- Later -/

Now that everything was finished, the city was once again bustling with activities, preparing for the harvest festival like nothing happened. For the mages of Fairy Tail, everything was better now. They were all healed, except Natsu and Gajeel who looked more like mummies at the moment, wrapped up in bandages. As for the culprits, only Luxus was heavily punished by the master, being excommunicated from the guild, but he left without protest. As for the Raijinshu, they were allowed to stay at Fairy Tail, even though Evergreen and Bickslow didn't wanted Luxus to go alone, they tried to follow him but Freed kept them by his side. As for the Riders, they talked about what happened since Sento came here.

\- "How many ?"

\- "You left for 1 month already." Ryuga said, answering Sento. "Why ?"

\- "I've been here for 4 month, which means that 1 month here is 1 week at home." He deduced, Ryuga nodding before chaining with Shocker. ""So Shocker is trying to find those dark magic artifact to use them in our world ?"

\- "Yeah. But I have the feeling that it's not just that. There is something else but I can't found what."

\- "Guess we'll have to find out what and soon."

Ryuga just resumed what their plan will be, but it won't be easy. But at least, now Sento had someone to help him who knew about Shocker and with his Best Match, he knew he could do it.

 **HERE IS RYUGA !** **I hope you liked it !**

 **I would like to talk to you a little, mainly about how I'll use the different arcs. Oracion Seis will be used like the other. Edolas will happen but Sento and Ryuga won't be part of it. They'll be outside the city when it happen, but they'll be here for the return, the meeting with the Exceeds and Lisanna's return. I'll use Tenrou too. For the grand magic games and Eclipse, I'll use the GMG to introduce new things, best match mainly, and even if they'll leave the city for good reason, they'll be back to finish the fight with the dragons. Tartaros will be used but I'll really focus on the Rider and their part of the story. As for the After Tartaros, I'll probably go straight to the final fight, since I got a pretty good idea for it. I hope you won't mind, after all, like I already said, it's my first story so I try to keep it 'simple'.**

 **See you next time !**

 **Next Time : To take down the dark guild ! The young sky maiden ! A come back and a perversion ! Welcome aboard the train of despair !**


	20. Author note : Adoption

OK guys. I would like to tell you that i'm putting this story up for adoption. I'm beginning to lose my motivation, and since i would like to see this story continue, i'm asking you to see if someone would like to take it.

I don't really know how adoption work so a little help could be good.

Also, just to make things clear, it's not impossible that one day, i'll continue this story, should it be not adopted. But for now, it's on standby. I'll be writing other fic surely, in french most of the time, some might get translation. it will depend on my mood.

Thank you all for following this story.

Good bye for now.


	21. Adopted !

Hey guys, it's been a long time and if i'm here today, it's to inform all of you that my fic has been adopted. There are some things that need to be done between us, but it's official, my fic is going to be taken by someone else, namely . I'll keep you updated about it, i'll tell you when he'll publish his version and all, he hopes to be ready by next month.

Thanks you all again for your support and just so you know, there is a small possibility that one day, i'll write a new fic like this one. So stay tuned.

Thanks again !

Erzats, over.


	22. Announcement

Hello guys !

It's been a long time. Like you probably already know, this fic has been adopted by someone but i still have no news. Since it's been a long time ago and that i felt like going back on a Kamen Rider x Fairy Tail crossover, i'm starting a new fic.

You'll find it under my profile. It goes by the name "Riders in Fiore". it will be heavily inspired by another well known crossover, "Neo-Heisei Rider Tail". It's more or less my take on that fic.

So if you're interested, go check it out.

Thank you all for your attention.

See ya !


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